Publisher: ASA   (Total: 2 journals)   [Sort by number of followers]

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J. of the Acoustical Society of America     Full-text available via subscription   (Followers: 58, SJR: 0.695, CiteScore: 2)
Proceedings of Meetings on Acoustics     Open Access   (Followers: 14)
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Journal of the Acoustical Society of America
Journal Prestige (SJR): 0.695
Citation Impact (citeScore): 2
Number of Followers: 58  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 0001-4966 - ISSN (Online) 1520-8524
Published by ASA Homepage  [2 journals]
  • Propagation of classical and low booms through kinematic turbulence with
           uncertain parameters

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      Authors: Roman Leconte, Jean-Camille Chassaing, François Coulouvrat, Régis Marchiano
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4207-4227, June 2022.
      The propagation of sonic boom through kinematic turbulence is known to have an important impact on the noise perceived at the ground. In this work, a recent numerical method called FLHOWARD3D based on a one-way approach is used to simulate the propagation of classical and low-boom waveforms. Kinematic turbulence is synthesized following a von Kármán energy spectrum. Two- and three-dimensional (2D and 3D) simulations are compared to experimental measurements, and 2D simulations are found to be slightly less accurate than 3D ones but still consistent with experimental levels around 98% of the time. A stochastic study is carried out on the 2D simulation using the generalized polynomial chaos method with parameters of the von Kármán spectrum as uncertain parameters. Differences between the propagation of a classical N-wave and low booms are observed: the classical N-wave shows higher peak pressure and variations than low-boom signatures. The standard deviation for the peak pressure, the D-weighted sound exposure level (D-SEL), and the perceived level in dB (PLdB) metrics all show a linear increase with the distance, with a faster increase for the classical N-wave for the peak pressure and D-SEL and a similar increase between the different booms for PLdB. In general, it is found that low-boom waveforms show less sensitivity to turbulence.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-27T12:04:49Z
       
  • Ray-based blind deconvolution with maximum kurtosis phase correction

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      Authors: Seunghyun Yoon, Haesang Yang, Woojae Seong
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4237-4251, June 2022.
      Ray-based blind deconvolution (RBD) is a method that estimates the source waveform and channel impulse response (CIR) using the ray arrival in an underwater environment. The RBD estimates the phase of the source waveform by using beamforming. However, low sampling, array shape deformation, and other factors can cause phase errors in the beamforming results. In this paper, phase correction is applied to the beamforming estimated source phase to improve RBD performance. The impulsiveness of the CIR was used as additional information to correct the initially estimated source phase. Kurtosis was used to measure impulsiveness, and the phase correction that maximized the kurtosis of the CIRs was calculated through optimization. The proposed approach is called ray-based blind deconvolution with maximum kurtosis phase correction (RBD-MKPC) and is based on a single-input multiple-output system. The RBD-MKPC was tested with several CIRs and source waveform combinations in the shallow-water acoustic variability experiment 2015 using broadband high-frequency pulses (11–31 kHz) as the source and a sparse vertical 16-element line array as receivers. The results indicate that the RBD-MKPC improves the estimation performance. In addition, from an optimization point of view and compared with other initialization methods, the proposed method showed superior convergence speed and estimation performance.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-27T12:04:46Z
       
  • Ultrasonic backscatter coefficient estimation in nonlinear regime using an
           in situ calibration target

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      Authors: Andres Coila, Michael L. Oelze
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4196-4206, June 2022.
      Tissue characterization based on the backscatter coefficient (BSC) can be degraded by acoustic nonlinearity. Often, this degradation is due to the method used for obtaining a reference spectrum, i.e., using a planar reference in water compared to a reference phantom approach resulted in more degradation. We hypothesize that an in situ calibration approach can improve BSC estimates in the nonlinear regime compared to using the reference phantom approach. The in situ calibration target provides a reference within the medium being interrogated and, therefore, nonlinear effects would already be contained in the in situ reference signal. Simulations and experiments in phantoms and in vivo were performed. A 2 mm diameter titanium bead was embedded in the interrogated media. An L9-4/38 probe (BK Ultrasound, Peabody, MA) and an analysis bandwidth from 4.5 to 7.4 MHz were used in experiments. Radiofrequency data from the sample, bead, and reference phantoms were acquired at a quasi-linear baseline power level and at further increments of output power. Better agreement between the BSC obtained at low power compared to high power was observed for the in situ calibration compared to the reference phantom approach.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-27T12:04:44Z
       
  • Effect of interaction of adjacent unit-cells on wave propagation in
           coupled mass-in-mass metamaterials

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      Authors: Pengcheng Zhao, Kai Zhang, Yunchan Fu, Zichen Deng
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4228-4236, June 2022.
      This paper aims to study the effect of the interaction of adjacent unit-cells in coupled mass-in-mass metamaterial on wave behaviors, which enables us to achieve a wavy dispersion relationship. Elastic wave propagation in a coupled mass-in-mass metamaterial is investigated to clarify the effect of the interaction of adjacent unit-cells on the dispersion relation and wave velocity. Elastic wave behavior based on an infinite system is studied in terms of the band structure and group velocity. The dynamic responses in frequency domain and time domain of the finite mass-in-mass lattice are calculated by using Laplace transform and numerical methods. The band structures and transmittances show that the coupled mass-in-mass metamaterial has a bandgap, which can be used to suppress and isolate vibration. The parameter study shows that changing the stiffness and location of the coupled springs can adjust the distribution of the bandgap. Importantly, we also calculate the ratio of group velocity to phase velocity that indicates the negative group velocity appearing in the wavy dispersion relation of coupled mass-in-mass metamaterials. These results show that the interaction of adjacent unit-cells plays a crucial role in the wave behavior of the coupled mass-in-mass metamaterial.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-27T12:04:44Z
       
  • Data augmentation aided complex-valued network for channel estimation in
           underwater acoustic orthogonal frequency division multiplexing system

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      Authors: Yonglin Zhang, Haibin Wang, Chao Li, Fabrice Meriaudeau
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4150-4164, June 2022.
      In this paper, a data augmentation aided complex-valued network is proposed for underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) channel estimations, wherein empirical mode decomposition based data augmentation is proposed to solve the current dilemma in the deep learning embedded UWA-OFDM communications: data scarcity and data-sampling difficulties in real-world applications. In addition, the significance of high-frequency component augmentation for the UWA channel and how it positively influences the following model training are discussed in detail and demonstrated experimentally in this paper. In addition, the complex-valued network is specially designed for the complex-formatted UWA-OFDM signal, which can fully utilize the relationship between its real and imaginary parts with half of the spatial resources of its real-valued counterparts. The experiments with the at-sea-measured WATERMARK dataset indicate that the proposed method can perform a near-optimal channel estimation, and its low resource requirements (on dataset and model) make it more adaptable to real-world UWA applications.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-23T12:31:07Z
       
  • Controlling the force and the position of acoustic traps with a tunable
           acoustofluidic chip: Application to spheroid manipulations

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      Authors: Nathan Jeger-Madiot, Xavier Mousset, Chloé Dupuis, Lucile Rabiet, Mauricio Hoyos, Jean-Michel Peyrin, Jean-Luc Aider
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4165-4179, June 2022.
      A multi-node acoustofluidic chip working on a broadband spectrum and beyond the resonance is designed for cell manipulations. A simple one-dimensional (1D) multi-layer model is used to describe the stationary standing waves generated inside a cavity. The transmissions and reflections of the acoustic wave through the different layers and interfaces lead to the creation of pressure nodes away from the resonance condition. A transparent cavity and a broadband ultrasonic transducer allow the measurement of the acoustic energy over a wide frequency range using particle image velocimetry measurements and the relation between acoustic energy and the particles velocity. The automation of the setup allows the acquisition over a large spectrum with a high frequency definition. The results show a wide continuous operating range for the acoustofluidic chip, which compares well with the 1D model. The variation of the acoustic radiation force when varying the frequency can be compensated to ensure a constant amplitude for the ARF. This approach is finally applied to mesenchymal stem cell (MCS) spheroids cultured in acoustic levitation. The MSC spheroids can be moved and merged just by varying the acoustic frequency. This approach opens the path to various acoustic manipulations and to complex 3D tissue engineering in acoustic levitation.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-23T12:31:06Z
       
  • Multi-method modeling to predict the onset conditions and resonance of the
           piezo coupled thermoacoustic engine

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      Authors: Fawad Ahmed, Guoyao Yu, Ercang Luo
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4180-4195, June 2022.
      This article seeks to perform a combination of methodologies to fully model and evaluate the rudimentary performance of a thermoacoustic engine integrated with a piezoelectric energy harvester (TAP). First, the root locus method was employed to determine the critical design operating values of the thermoacoustic engine. Later, a lumped parameter model was developed as a matlab Simulink program to calculate the transient temperature and pressure responses of the thermoacoustic engine. In addition, a two-element reduced model (executed on matlab) and finite element analysis tools were used to simulate and assess the performance of aluminum-piezo (lead zirconate titanate (PZT-5H) and lead manganese niobate-lead titanate (PMN-PT)) disks that are to be integrated with the thermoacoustic engine. Last but most importantly, the piezo-diaphragm and thermoacoustic engine were coupled using the electrical analogy technique through which the onset conditions and resonance frequency of the integrated TAP system were determined. We take a traveling wave thermoacoustic engine and a commercially available piezoelectric disk as a test case for the analysis. It is concluded that the outcomes from the multiple methods are in good agreement with the experimental results.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-23T12:31:05Z
       
  • Singing in different performance spaces: The effect of room acoustics on
           vibrato and pitch inaccuracy

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      Authors: Pasquale Bottalico, Natalia Łastowiecka, Joshua D. Glasner, Yvonne Gonzales Redman
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4131-4139, June 2022.
      Previous literature suggests that musical performers may be influenced to some extent by the acoustic environment in which they sing or play. This study investigates the influence of room acoustics on singers' voice production, by analyzing consecutive sung performances of classically trained students in five different performance spaces. The analyzed voice parameters were vibrato rate, extent, and pitch inaccuracy. Nine classically trained student-singers performed the same aria unaccompanied on a variable starting pitch that was consistent between spaces. Variance in vibrato rate and pitch inaccuracy was primarily explained by individual differences between singers. Conversely, the variance attributable to the rooms for the parameter of vibrato extent was larger compared to the variance attributable to the performers. Vibrato extent tended to increase with room clarity (C80) and was inversely associated with early decay time (EDT). Additionally, pitch inaccuracy showed a significant negative association with room support (STv). Singers seem to adjust their vocal production when performing in different acoustic environments. Likewise, the degree to which a singer can hear themself on stage may influence pitch accuracy.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-22T11:33:02Z
       
  • Label distribution-guided transfer learning for underwater source
           localization

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      Authors: Feng-Xiang Ge, Yanyu Bai, Mengjia Li, Guangping Zhu, Jingwei Yin
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4140-4149, June 2022.
      Underwater source localization by deep neural networks (DNNs) is challenging since training these DNNs generally requires a large amount of experimental data and is computationally expensive. In this paper, label distribution-guided transfer learning (LD-TL) for underwater source localization is proposed, where a one-dimensional convolutional neural network (1D-CNN) is pre-trained with the simulation data generated by an underwater acoustic propagation model and then fine-tuned with a very limited amount of experimental data. In particular, the experimental data for fine-tuning the pre-trained 1D-CNN are labeled with label distribution vectors instead of one-hot encoded vectors. Experimental results show that the performance of underwater source localization with a very limited amount of experimental data is significantly improved by the proposed LD-TL.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-22T11:33:00Z
       
  • Robust underwater direction-of-arrival tracking with uncertain
           environmental disturbances using a uniform circular hydrophone array

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      Authors: Boxuan Zhang, Xianghao Hou, Yixin Yang
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4101-4113, June 2022.
      Underwater direction-of-arrival (DOA) tracking using a hydrophone array is an important research subject in passive sonar signal processing. In this study, considering that an unknown underwater environment results in uncertain disturbances to the measurements, robust underwater DOA tracking with regard to uncertain environmental disturbances was studied. Because the uniform circular array (UCA) is free from the port and starboard ambiguity problem, a UCA was used to obtain the measurements for a long-time tracking scenario. First, a kinematic model of an underwater target and a measurement model based on the received signal of the UCA were established. Then, a DOA tracking algorithm was derived based on the extended Kalman filter (EKF), whose performance is significantly affected by the accuracy of the measurement noise covariance matrix (MNCM). Finally, considering that uncertain disturbances carry out unstable measurement noise, the modified Sage–Husa algorithm was used to obtain accurate MNCMs during the process of the derived EKF-based DOA tracking algorithm. Thus, a robust DOA tracking method with uncertain environmental disturbances using a UCA was proposed. The accuracy and reliability of the suggested method was verified via Monte Carlo simulations of a DOA tracking scenario and an experiment in the South China Sea in July 2021.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-21T11:37:55Z
       
  • Towards a practical methodology for assessment of the objective occlusion
           effect induced by earplugs

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      Authors: Hugo Saint-Gaudens, Hugues Nélisse, Franck Sgard, Olivier Doutres
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4086-4100, June 2022.
      The occlusion effect (OE) occurs when the earcanal becomes occluded by an in-ear device, sometimes leading to discomforts experienced by the users due to the augmented perception of physiological noises, or to a distorted perception of one's own voice. The OE can be assessed objectively by measuring the amplification of the low-frequency sound pressure level (SPL) in the earcanal using in-ear microphones. However, as revealed by methodological discrepancies found in past studies, the measurement of this objective occlusion effect (OEobj) is not standardized. With the goal of proposing a robust yet simple methodology adapted for field assessment, three experimental aspects are investigated: (i) stimulation source and the stimulus's characteristics to induce the phenomenon, (ii) measurement method of the SPL in earcanal, (iii) indicator to quantify the OEobj. To do so, OEobj is measured on human participants in laboratory conditions. Results obtained with a specific insert device suggest using the participant's own voice combined with simultaneous measurements of the SPLs based on the noise reduction method and using a single value indicator leads to a simple yet robust methodology to assess OEobj. Further research is necessary to validate the results with other devices and to generalize the methodology for field assessment.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-21T11:37:55Z
       
  • On the scattering of a disk source by a rigid sphere for directivity
           broadening

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      Authors: Tim Mellow, Leo Kärkkäinen
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4114-4125, June 2022.
      The purpose of this study is to model a circular planar loudspeaker placed near a spherical reflector to broaden its directivity pattern, which would otherwise become increasingly narrow at high frequencies. Through ray tracing, it seems intuitively feasible to thus create a virtual point source at very high frequencies, but we provide a more rigorous analysis to determine what will happen at intermediate frequencies where the wavelength is of a similar magnitude to the diameter of the disk or sphere. We show that a smoother off-axis response is obtained with a dipole pressure source, which does not obstruct the scattered sound, rather than a monopole velocity source. Hence, an electrostatic loudspeaker, for example, would be more suitable than a dynamic one. The sphere may also serve as a spherical approximation of a human head, in which case the loudspeaker would become an open headphone that is not sealed to the ear.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-21T11:37:53Z
       
  • Efficient independent vector extraction of dominant source (L)

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      Authors: Lele Liao, Guoliang Cheng, Zhaoyi Gu, Jing Lu
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4126-4130, June 2022.
      The complete decomposition performed by blind source separation is computationally demanding and superfluous when only the speech of one specific target speaker is desired. This letter proposes a computationally efficient blind source extraction method based on the fast fixed-point optimization algorithm under the mild assumption that the average power of the source of interest outweighs the interfering sources. Moreover, a one-unit scaling operation is designed to solve the scaling ambiguity for source extraction. Experiments validate the efficacy of the proposed method in extracting the dominant source.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-21T11:37:52Z
       
  • Shadow radiation and Fresnel diffraction of acoustic waves

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      Authors: Pyotr Ya. Ufimtsev, Gokhan Apaydin, Levent Sevgi
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4063-4072, June 2022.
      Fresnel diffraction is a fundamental wave phenomenon. This article explains its physical nature using the examples of the diffraction of acoustic waves at soft and hard half-planes and at large apertures on a black screen. It is shown that the shadow radiation by opaque screens plays a central role in these diffraction phenomena. Fresnel–Kirchhoff diffraction at large apertures is presented as an asymptotic form of the shadow radiation. Fresnel and Grimaldi-type diffraction at the soft and hard half-planes is revealed as interference of the shadow radiation and the incident wave.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-17T12:23:23Z
       
  • Mesopelagic fish gas bladder elongation, as estimated from wideband
           acoustic backscattering measurements

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      Authors: Babak Khodabandeloo, Egil Ona, Geir Pedersen, Rolf Korneliussen, Webjørn Melle, Thor Klevjer
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4073-4085, June 2022.
      Backscattered acoustic energy from a target varies with frequency and carries information about its material properties, size, shape, and orientation. Gas-bearing organisms are strong reflectors of acoustic energy at the commonly used frequencies (∼18–450 kHz) in fishery surveys, but lack of knowledge of their acoustic properties creates large uncertainties in mesopelagic biomass estimates. Improved knowledge about the volume and elongation (i.e., longest to shortest dimension) of swimbladders of mesopelagic fishes has been identified as an important factor to reduce the overall uncertainties in acoustic survey estimates of mesopelagic biomass. In this paper, a finite element approach was used to model gas-filled objects, revealing the structure of the backscattering, also at frequencies well above the main resonance frequency. Similar scattering features were observed in measured broadband backscattering of several individual mesopelagic organisms. A method is suggested for estimating the elongation of a gas-bubble using these features. The method is applied to the in situ measured wideband (33–380 kHz) target strength (TS) of single mesopelagic gas-bearing organisms from two stations in the North Atlantic (NA) and Norwegian Sea (NS). For the selected targets, the method suggested that the average elongation of gas-bladder at the NA and NS stations are 1.49 ± 0.52 and 2.86 ± 0.50, respectively.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-17T12:23:21Z
       
  • A coherence-based phase and amplitude gradient estimator method for
           calculating active acoustic intensity

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      Authors: Mylan R. Cook, Kent L. Gee, Scott D. Sommerfeldt
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4053-4060, June 2022.
      The phase and amplitude gradient estimator (PAGE) method [Thomas, Christensen, and Gee, J. Acoust. Soc. Am. 137, 3366–3376 (2015)] has been developed as an alternative to the traditional p-p method for calculating energy-based acoustic measures such as active acoustic intensity. While this method shows many marked improvements over the traditional method, such as a wider valid frequency bandwidth for broadband sources, contaminating noise can lead to inaccurate results. Contaminating noise degrades performance for both the traditional and PAGE methods and causes probe microphone pairs to exhibit low coherence. When coherence is low, better estimates of the pressure magnitude and gradient can be obtained by using a coherence-based approach, which yields a more accurate intensity estimate. This coherence-based approach to the PAGE method, known as the CPAGE method, employs two main coherence-based adjustments. The pressure magnitude adjustment mitigates the negative impact of uncorrelated contaminating noise and improves intensity magnitude calculation. The phase gradient adjustment uses coherence as a weighting to calculate the phase gradient for the probe and improves primarily the calculation of intensity direction. Though requiring a greater computation time than the PAGE method, the CPAGE method is shown to improve intensity calculations, both in magnitude and direction.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-16T12:31:03Z
       
  • Erratum: Assessing potential perception of shipping noise by marine
           mammals in an arctic inlet [J. Acoust. Soc. Am. 151, 2310–2325 (2022)]

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      Authors: Samuel O. Sweeney, John M. Terhune, Héloïse Frouin-Mouy, Philippe A. Rouget
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4061-4062, June 2022.

      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-16T12:31:00Z
       
  • An iterative transfer matrix approach for estimating the sound speed and
           attenuation constant of air in a standing wave tube

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      Authors: Zhuang Mo, Guochenhao Song, Kang Hou, J. Stuart Bolton
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4016-4027, June 2022.
      In this work, an iterative method based on the four-microphone transfer matrix approach was developed for evaluating the sound speed and attenuation constant of air within a standing wave tube. When the air inside the standing wave tube is treated as the material under test, i.e., as if it were a sample of porous material, the transfer matrix approach can be used to identify the air's acoustic properties. The wavenumber within the tube is complex owing to the formation of a visco-thermal boundary layer on the inner circumference of the tube. Starting from an assumed knowledge of the air properties, an iterative method can be applied in the post-processing stage to estimate the complex wavenumber. Experimental results presented here show that although the results are sensitive to ambient temperature, a semi-empirical formula previously proposed by Temkin [(1981). Elements of Acoustics (John Wiley & Sons)] matches closely with the measured sound speed and attenuation constant, as does a theoretical formulation proposed by Lahiri et al. [(2014). J. Sound Vib. 333(15), 3440–3458]. Further, it is shown that the Temkin [(1981). Elements of Acoustics (John Wiley & Sons)] and Lahiri et al. [(2014). J. Sound Vib. 333(15), 3440–3458] predictions accurately represent the variation of sound speed with frequency, in contrast to the formula recommended in the ASTM E1050 standard [(2019). American Society for Testing and Materials], in which the sound speed is assumed to be independent of frequency.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-15T12:34:23Z
       
  • Effect of bat pinna on sensing using acoustic finite difference time
           domain simulation

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      Authors: Yu Teshima, Takumi Nomura, Megumi Kato, Takao Tsuchiya, Genki Shimizu, Shizuko Hiryu
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4039-4045, June 2022.
      The practicality of the finite-difference time-domain (FDTD) method was confirmed by comparing head-related transfer functions obtained from a three-dimensional (3D) digital model of a bat (Rhinolophus ferrumequinum nippon) head with acoustic experiments using a 3D printed physical model. Furthermore, we simulated the auditory directionality using a 3D digital model that was modified based on the pinna movement of a bat during echolocation and found that the alternating movements of the left and right pinna result in a binaural sound pressure difference for vertical sources. Using the FDTD method, suitable for simulating acoustics in large spaces, we could analyze in detail the binaural echoes that bats receive and the acoustic cues they use for echolocation.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-15T12:34:22Z
       
  • Formant detail needed for identifying, rating, and discriminating vowels
           in Wisconsin English

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      Authors: Jonathan Jibson
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4004-4015, June 2022.
      Neel [(2004). Acoust. Res. Lett. Online 5, 125–131] asked how much time-varying formant detail is needed for vowel identification. In that study, multiple stimuli were synthesized for each vowel: 1-point (monophthongal with midpoint frequencies), 2-point (linear from onset to offset), 3-point, 5-point, and 11-point. Results suggested that a 3-point model was optimal. This conflicted with the dual-target hypothesis of vowel inherent spectral change research, which has found that two targets are sufficient to model vowel identification. The present study replicates and expands upon the work of Neel. Ten English monophthongs were chosen for synthesis. One-, two-, three-, and five-point vowels were created as described above, and another 1-point stimulus was created with onset frequencies rather than midpoint frequencies. Three experiments were administered (n = 18 for each): vowel identification, goodness rating, and discrimination. The results ultimately align with the dual-target hypothesis, consistent with most vowel inherent spectral change studies.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-15T12:34:19Z
       
  • Open set classification strategies for long-term environmental field
           recordings for bird species recognition

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      Authors: Mallory M. Morgan, Jonas Braasch
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4028-4038, June 2022.
      Deep learning is one established tool for carrying out classification tasks on complex, multi-dimensional data. Since audio recordings contain a frequency and temporal component, long-term monitoring of bioacoustics recordings is made more feasible with these computational frameworks. Unfortunately, these neural networks are rarely designed for the task of open set classification in which examples belonging to the training classes must not only be correctly classified but also crucially separated from any spurious or unknown classes. To combat this reliance on closed set classifiers which are singularly inappropriate for monitoring applications in which many non-relevant sounds are likely to be encountered, the performance of several open set classification frameworks is compared on environmental audio datasets recorded and published within this work, containing both biological and anthropogenic sounds. The inference-based open set classification techniques include prediction score thresholding, distance-based thresholding, and OpenMax. Each open set classification technique is evaluated under multi-, single-, and cross-corpus scenarios for two different types of unknown data, configured to highlight common challenges inherent to real-world classification tasks. The performance of each method is highly dependent upon the degree of similarity between the training, testing, and unknown domain.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-15T12:34:18Z
       
  • An algebraic correction for the Westervelt equation to account for the
           local nonlinear effects in parametric acoustic array

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      Authors: Milan Červenka, Michal Bednařík
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 4046-4052, June 2022.
      This work presents a simple computational approach for the calculation of parametrically generated low-frequency sound fields. The Westervelt wave equation is employed as a model equation that accounts for the wave diffraction, attenuation, and nonlinearity. As it is known that the Westervelt equation captures the cumulative nonlinear effects correctly and not the local ones, an algebraic correction is proposed, which includes the local nonlinear effects in the solution of the Westervelt equation. This way, existing computational approaches for the Westervelt equation can be used even in situations where the generated acoustic field differs significantly from the plane progressive waves, such as in the near-field, and where the local effects manifest themselves strongly. The proposed approach is demonstrated and validated on an example of the parametric radiation from a baffled circular piston.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-15T12:34:16Z
       
  • Field attenuation characteristics of hearing protectors and differences in
           estimating their attenuation with different methods

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      Authors: Wei Gong, Yanqiong Xu, Yufei Liu
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3979-3992, June 2022.
      This study investigated the field attenuation characteristics of hearing protection devices (HPDs), differences in estimating the protection provided by HPDs with different rating methods, and suggested potential solutions on proper use of attenuation ratings to estimate the protection provided by HPDs. The binaural octave-band personal attenuation values obtained from 1583 field users with 3985 fits on seven HPDs were used to compute the field-rating values as described in the International Organization for Standardization standard ISO 4869-2:2018, and the octave-band noise reduction (OB NR) values of each fit for 100 noises. The estimated protection for 100 noises was compared within different rating methods. The OB NR values varied with quality of fit, noise spectra, and HPD. The quality of fit was a crucial factor. Deviations in estimating the protection given by different rating methods varied with HPD and quality of fit. The misuse of subtracting the single number rating (SNR) from A-weighted noise level magnified these deviations. The multiple-number rating gave a more accurate estimation of protection provided by the earmuff compared to SNR. Improving the quality of fit and including C-weighted noise level can reduce the variability and deviation in protection estimation for different noises.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-14T05:00:38Z
       
  • Time-resolved absolute radius estimation of vibrating contrast
           microbubbles using an acoustical camera

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      Authors: Sander Spiekhout, Jason Voorneveld, Benjamin van Elburg, Guillaume Renaud, Tim Segers, Guillaume P. R. Lajoinie, Michel Versluis, Martin D. Verweij, Nico de Jong, Johannes G. Bosch
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3993-4003, June 2022.
      Ultrasound (US) contrast agents consist of microbubbles ranging from 1 to 10 μm in size. The acoustical response of individual microbubbles can be studied with high-frame-rate optics or an “acoustical camera” (AC). The AC measures the relative microbubble oscillation while the optical camera measures the absolute oscillation. In this article, the capabilities of the AC are extended to measure the absolute oscillations. In the AC setup, microbubbles are insonified with a high- (25 MHz) and low-frequency US wave (1–2.5 MHz). Other than the amplitude modulation (AM) from the relative size change of the microbubble (employed in Renaud, Bosch, van der Steen, and de Jong (2012a). “An ‘acoustical camera’ for in vitro characterization of contrast agent microbubble vibrations,” Appl. Phys. Lett. 100(10), 101911, the high-frequency response from individual vibrating microbubbles contains a phase modulation (PM) from the microbubble wall displacement, which is the extension described here. The ratio of PM and AM is used to determine the absolute radius, R0. To test this sizing, the size distributions of two monodisperse microbubble populations ([math] 2.1 and 3.5 μm) acquired with the AC were matched to the distribution acquired with a Coulter counter. As a result of measuring the absolute size of the microbubbles, this “extended AC” can capture the full radial dynamics of single freely floating microbubbles with a throughput of hundreds of microbubbles per hour.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-14T05:00:36Z
       
  • A neurotrophic approach to treating hearing loss: Translation from animal
           models to clinical proof-of-concept

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      Authors: Alan C. Foster, Stephanie Szobota, Fabrice Piu, Bonnie E. Jacques, David R. Moore, Victoria A. Sanchez, Jeffery J. Anderson
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3937-3946, June 2022.
      Currently, there are no approved medicines available for the treatment of hearing loss. However, research over the past two decades has contributed to a growing understanding of the pathological mechanisms in the cochlea that result in hearing difficulties. The concept that a loss of the synapses connecting inner hair cells with the auditory nerve (cochlear synaptopathy) contributes to hearing loss has gained considerable attention. Both animal and human post-mortem studies support the idea that these synapses (ribbon synapses) are highly vulnerable to noise, ototoxicity, and the aging process. Their degeneration has been suggested as an important factor in the speech-in-noise difficulties commonly experienced by those suffering with hearing loss. Neurotrophins such as brain derived neurotrophic factor (BDNF) have the potential to restore these synapses and provide improved hearing function. OTO-413 is a sustained exposure formulation of BDNF suitable for intratympanic administration that in preclinical models has shown the ability to restore ribbon synapses and provide functional hearing benefit. A phase 1/2 clinical trial with OTO-413 has provided initial proof-of-concept for improved speech-in-noise hearing performance in subjects with hearing loss. Key considerations for the design of this clinical study, including aspects of the speech-in-noise assessments, are discussed.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-13T12:43:45Z
       
  • Marine compressed air source array primary acoustic field characterization
           from at-sea measurements

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      Authors: Natalia Sidorovskaia, Kun Li
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3957-3978, June 2022.
      The primary acoustic field of a standard seismic survey source array is described based on a calibrated dataset collected in the Gulf of Mexico. Three vertical array moorings were deployed to measure the full dynamic range and bandwidth of the acoustic field emitted by the compressed air source array. The designated source vessel followed a specified set of survey lines to provide a dataset with broad coverage of ranges and departure angles from the array. Acoustic metrics relevant to criteria associated with potential impacts on marine life are calculated from the recorded data. Sound pressure levels from direct arrivals exhibit large variability for a fixed distance between source and receiver; this indicates that the distance cannot be reliably used as a single parameter to derive meaningful exposure levels for a moving source array. The far-field acoustic metrics' variations with distance along the true acoustic path for a narrow angular bin are accurately predicted using a simplified model of the surface-affected source waveform, which is a function of the direction. The presented acoustic metrics can be used for benchmarking existing source/propagation models for predicting acoustic fields of seismic source arrays and developing simplified data-supported models for environmental impact assessments.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-13T12:43:44Z
       
  • Physical effects of sound exposure from underwater explosions on Pacific
           mackerel (Scomber japonicus): Effects on non-auditory tissues

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      Authors: A. Keith Jenkins, Peter H. Dahl, Sarah E. Kotecki, Victoria Bowman, Brandon Casper, Christiana Boerger, Arthur N. Popper
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3947-3956, June 2022.
      Underwater explosions from activities such as construction, demolition, and military activities can damage non-auditory tissues in fishes. To better understand these effects, Pacific mackerel (Scomber japonicus) were placed in mid-depth cages with water depth of approximately 19.5 m and exposed at distances of 21 to 807 m to a single mid-depth detonation of C4 explosive (6.2 kg net explosive weight). Following exposure, potential correlations between blast acoustics and observed physical effects were examined. Primary effects were damage to the swim bladder and kidney that exceeded control levels at ≤333 m from the explosion [peak sound pressure level 226 dB re 1 μPa, sound exposure level (SEL) 196 dB re 1 μPa2 s, pressure impulse 98 Pa s]. A proportion of fish were dead upon retrieval at 26–40 min post exposure in 6 of 12 cages located ≤157 m from the explosion. All fish that died within this period suffered severe injuries, especially swim bladder and kidney rupture. Logistic regression models demonstrated that fish size or mass was not important in determining susceptibility to injury and that peak pressure and SEL were better predictors of injury than was pressure impulse.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-13T12:43:42Z
       
  • Lower interaural coherence in off-signal bands impairs binaural detection

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      Authors: Bernhard Eurich, Jörg Encke, Stephan D. Ewert, Mathias Dietz
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3927-3936, June 2022.
      Differences in interaural phase configuration between a target and a masker can lead to substantial binaural unmasking. This effect is decreased for masking noises with an interaural time difference (ITD). Adding a second noise with an opposing ITD in most cases further reduces binaural unmasking. Thus far, modeling of these detection thresholds required both a mechanism for internal ITD compensation and an increased filter bandwidth. An alternative explanation for the reduction is that unmasking is impaired by the lower interaural coherence in off-frequency regions caused by the second masker [Marquardt and McAlpine (2009). J. Acoust. Soc. Am. 126(6), EL177–EL182]. Based on this hypothesis, the current work proposes a quantitative multi-channel model using monaurally derived peripheral filter bandwidths and an across-channel incoherence interference mechanism. This mechanism differs from wider filters since it has no effect when the masker coherence is constant across frequency bands. Combined with a monaural energy discrimination pathway, the model predicts the differences between a single delayed noise and two opposingly delayed noises as well as four other data sets. It helps resolve the inconsistency that simulating some data requires wide filters while others require narrow filters.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-10T12:34:21Z
       
  • Developing experimental skills: A hands-on course in acoustical
           measurement techniques at the Norwegian University of Science and
           Technology

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      Authors: Hefeng Dong, U. Peter Svensson, Guillaume Dutilleux, Sara R. Martin, Tim Cato Netland, Robin André Rørstadbotnen, Andreas Sørbrøden Talberg
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3919-3926, June 2022.
      The course “Acoustical Measurement Techniques TTT4250,” offered by the Acoustics Group at the Department of Electronic Systems, Norwegian University of Science and Technology, is a fourth-year course in the specialization of acoustics in the five-year master program “Electronics Systems Design and Innovation” or MTELSYS, and the two-year international master program “Electronic Systems Design” or MSELSYS. It is one of the four required courses for MTELSYS and one of the two required courses for MSELSYS. It offers a hands-on approach to acoustics. This paper outlines the topics covered in this course and the involvement of several academic staff members, as well as invited industry and research institute guest speakers, as teachers. The assessment of laboratory reports is described, and general lecture topics, including measurement uncertainty and statistics, the introduction of standards, and programming, are also described. All aspects of the course aim to maximize students' experience with a broad range of acoustic measurements and their interest in acoustics.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-10T12:34:20Z
       
  • Theoretical and numerical simulation to control the wideband interfering
           noise by the broadband constant beam pattern method for a cylindrical
           array

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      Authors: Dehua Huang
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3886-3894, June 2022.
      The broadband azimuthal constant beam pattern (CBP) cylindrical array synthesis theory is applied to suppress or to cancel wideband interfering directional noise sources on this plane by implanting zeros in the array's original synthesized shading function. This modified array shading function can be expanded by Fourier cosine and sine series, which are converged to the beam pattern in the far-field such that the created nulls (or reduced-response beam sidelobes) are in the wideband interfering noise source directions per the CBP theory for the large ratio of the cylindrical array radius to the operating frequency wavelength. The simulated numerical examples given for this wideband noise source suppression method for modified Legendre polynomial, classic Dolph–Chebyshev, and Taylor shading functions maintain a broadband CBP performance in the azimuthal plane for a cylindrical array. With the CBP design, one set of the real shading functions works for all frequencies in the array's operating band to cancel or to suppress wideband interfering noise sources.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-09T12:31:49Z
       
  • Calculating the acoustic input impedance of a simplified brass instrument
           as an educational laboratory activity

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      Authors: Andrew Morrison, Randy Worland
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3858-3865, June 2022.
      The concept of acoustic impedance is often difficult for students in introductory acoustics courses to make sense of, especially students without advanced mathematics backgrounds. This work summarizes a laboratory activity for students in a general education musical acoustics class where a simplified brass musical instrument is examined, focusing on how the geometry of the air column affects the input impedance of the instrument. Students are guided through making bore profile measurements for use in a computation of the input impedance. Options for making experimental measurements of the simplified instrument are explained. The laboratory activity was successfully used with students who reported their increased understanding of the acoustics of brass musical instruments.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-09T12:31:48Z
       
  • Three-dimensional echo decorrelation monitoring of radiofrequency ablation
           in ex vivo bovine liver

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      Authors: E. Ghahramani Z, P. D. Grimm, K. J. Eary, M. P. Swearengen, E. G. Sunethra K. Dayavansha, T. D. Mast
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3907-3918, June 2022.
      Three-dimensional (3D) echo decorrelation imaging was investigated for monitoring radiofrequency ablation (RFA) in ex vivo bovine liver. RFA experiments (N = 14) were imaged by 3D ultrasound using a matrix array, with in-phase and quadrature complex echo volumes acquired about every 11 s. Tissue specimens were then frozen at −80 °C, sectioned, and semi-automatically segmented. Receiver operating characteristic (ROC) curves were constructed for assessing ablation prediction performance of 3D echo decorrelation with three potential normalization approaches, as well as 3D integrated backscatter (IBS). ROC analysis indicated that 3D echo decorrelation imaging is potentially a good predictor of local RFA, with the best prediction performance observed for globally normalized decorrelation. Tissue temperatures, recorded by four thermocouples integrated into the RFA probe, showed good correspondence with spatially averaged decorrelation and statistically significant but weak correlation with measured echo decorrelation at the same spatial locations. In tests predicting ablation zones using a weighted K-means clustering approach, echo decorrelation performed better than IBS, with smaller root mean square volume errors and higher Dice coefficients relative to measured ablation zones. These results suggest that 3D echo decorrelation and IBS imaging are capable of real-time monitoring of thermal ablation, with potential application to clinical treatment of liver tumors.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-09T12:31:47Z
       
  • Signal power distributions for simulated outdoor sound propagation in
           varying refractive conditions

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      Authors: D. Keith Wilson, Chris L. Pettit, Vladimir E. Ostashev, Matthew J. Kamrath
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3895-3906, June 2022.
      Probability distributions of acoustic signals propagating through the near-ground atmosphere are simulated by the parabolic equation method. The simulations involve propagation at four angles relative to the mean wind, with frequencies of 100, 200, 400, and 800 Hz. The environmental representation includes realistic atmospheric refractive profiles, turbulence, and ground interactions; cases are considered with and without parametric uncertainties in the wind velocity and surface heat flux. The simulated signals are found to span a broad range of scintillation indices, from near zero to exceeding ten. In the absence of uncertainties, the signal power (or intensity) is fit well by a two-parameter gamma distribution, regardless of the frequency and refractive conditions. When the uncertainties are included, three-parameter distributions, namely, the compound gamma or generalized gamma, are needed for a good fit to the simulation data. The compound gamma distribution appears preferable because its parameters have a straight forward interpretation related to the saturation and modulation of the signal by uncertainties.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-09T12:31:46Z
       
  • Assessment methods for determining small changes in hearing performance
           over time

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      Authors: Douglas S. Brungart, LaGuinn P. Sherlock, Stefanie E. Kuchinsky, Trevor T. Perry, Rebecca E. Bieber, Ken W. Grant, Joshua G. W. Bernstein
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3866-3885, June 2022.
      Although the behavioral pure-tone threshold audiogram is considered the gold standard for quantifying hearing loss, assessment of speech understanding, especially in noise, is more relevant to quality of life but is only partly related to the audiogram. Metrics of speech understanding in noise are therefore an attractive target for assessing hearing over time. However, speech-in-noise assessments have more potential sources of variability than pure-tone threshold measures, making it a challenge to obtain results reliable enough to detect small changes in performance. This review examines the benefits and limitations of speech-understanding metrics and their application to longitudinal hearing assessment, and identifies potential sources of variability, including learning effects, differences in item difficulty, and between- and within-individual variations in effort and motivation. We conclude by recommending the integration of non-speech auditory tests, which provide information about aspects of auditory health that have reduced variability and fewer central influences than speech tests, in parallel with the traditional audiogram and speech-based assessments.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-09T12:31:40Z
       
  • The dual influence of the reed resonance frequency and tonehole lattice
           cutoff frequency on sound production and radiation of a clarinet-like
           instrument

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      Authors: Erik Alan Petersen, Philippe Guillemain, Michaël Jousserand
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3780-3791, June 2022.
      The internal and external spectra of woodwind reed instruments are partially determined by the tonehole lattice cutoff and reed resonance frequencies. Because they can impact the spectrum in similar ways, a study of one without accounting for the other risks incomplete or false conclusions. Here, the dual effects of the cutoff and reed resonance frequencies are investigated using digital synthesis with clarinet-like academic resonators. It is shown that the odd and even harmonics have similar amplitudes at and above the cutoff frequency or reed resonance frequency, whichever is lowest. However, because the resonators radiate efficiently at the cutoff, it has the additional role of reinforcing the amplitude of both the odd and even harmonics in the external spectrum. The spectra are analyzed using the single value descriptors playing frequency, spectral centroid (SC), odd/even ratio (OER), and brightness as a function of the musician mouth pressure. Higher reed resonances correspond to higher values for all descriptors. The OER and brightness increase with resonator cutoff frequency, whereas the SC exhibits more complicated trends. The reed resonance has a larger impact on the “playing condition oscillation threshold,” implying that it may have a more important role in sustaining auto-oscillation.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-09T06:32:08Z
       
  • Spatial acuity of the bottlenose dolphin (Tursiops truncatus) biosonar
           system with a bat and human comparison

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      Authors: Brian K. Branstetter, Rachel Brietenstein, Gavin Goya, Megan Tormey, Teri Wu, James J. Finneran
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3847-3857, June 2022.
      Horizontal angular resolution was measured in two bottlenose dolphins using a two-alternative forced-choice, biosonar target discrimination paradigm. The task required a stationary dolphin positioned in a hoop to discriminate two physical targets at a range of 4 m. The angle separating the targets was manipulated to estimate an angular discrimination threshold of 1.5°. In a second experiment, a similar two-target biosonar discrimination task was conducted with one free-swimming dolphin, to test whether its emission beam was a critical factor in discriminating the targets. The spatial separation between two targets was manipulated to measure a discrimination threshold of 6.7 cm. There was a relationship between differences in acoustic signals received at each target and the dolphin's performance. The results of the angular resolution experiment were in good agreement with measures of the minimum audible angle of both dolphins and humans and remarkably similar to measures of angular difference discrimination in echolocating dolphins, bats, and humans. The results suggest that horizontal auditory spatial acuity may be a common feature of the mammalian auditory system rather than a specialized feature exclusive to echolocating auditory predators.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-08T12:51:43Z
       
  • Study of an acoustic energy harvester consisting of electro-spun
           polyvinylidene difluoride nanofibers

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      Authors: Ran Zhang, Hao Shao, Tong Lin, Xu Wang
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3838-3846, June 2022.
      Sound pollution has been capturing more and more attention around the world. Piezoelectric materials convert acoustic energy into electrical energy and actively attenuate the sound simultaneously. In this paper, an electro-spun nonwoven polyvinylidene difluoride nanofiber membrane as a high-performance piezoelectric material is found to have an ultra-high acoustoelectric conversion capability at the low sound frequency range. The novelty of the material in this paper is the proposed electro-spun piezoelectric nano-fiber web, which presents a strong acoustic-to-electric conversion performance. The piezoelectric acoustic energy harvester consists of the polyvinylidene difluoride nanofiber membrane that vibrates under the sound wave excitation. The piezoelectric acoustic energy harvester device can precisely detect the sound of 72.5 Hz with a sensitivity as high as 711.3 mV Pa−1 which is higher than the sensitivity of a commercial piezoelectric poly (vinylidene fluoride) membrane device. The energy harvesting performance of the piezoelectric acoustic energy harvester device is simulated by the comsol software and then validated with the experimental results to illustrate its excellent energy harvesting ability. Based on the validated simulation model, a regression parameter model is developed from the comsol software simulation results using the response surface method. The empirical regression parameter model is applied to predict the energy harvesting performance of the acoustic energy harvester from input design parameters or material property parameters where the sensitivity of the design parameters or material property parameters and their interactions can be analyzed. The design or material property parameters can be optimized for the best energy harvesting performance based on the regression parameter model. The optimization results show a significant improvement in the energy harvesting performance. The sensitivity of the parameters on the energy harvesting performance also indicates the potential of the large-scale application of this acoustic energy harvester.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-08T12:51:42Z
       
  • Gridless sparse covariance-based beamforming via alternating projections
           including co-prime arrays

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      Authors: Yongsung Park, Peter Gerstoft
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3828-3837, June 2022.
      This paper presents gridless sparse processing for direction-of-arrival (DOA) estimation. The method solves a gridless version of sparse covariance-based estimation using alternating projections. Gridless sparse DOA estimation is represented by the reconstruction of Toeplitz-structured low-rank matrices, which our method recovers by alternatively projecting a solution matrix. Compared to the existing gridless sparse methods, our method improves speed and accuracy and considers non-uniformly configured linear arrays. High-resolution and reliable DOA estimation are achieved even with single-snapshot data, coherent sources, and non-uniform arrays. Simulation results demonstrate performance improvements compared to the existing DOA estimators, including gridless sparse methods. The method is illustrated using experimental data from a real ocean experiment.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-08T12:51:39Z
       
  • Vector acoustic and polarization properties of underwater ship noise

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      Authors: Peter H. Dahl, Julien Bonnel
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3818-3827, June 2022.
      Vector acoustic field properties measured during the 2017 Seabed Characterization Experiment (SBCEX17) are presented. The measurements were made using the Intensity Vector Autonomous Recorder (IVAR) that records acoustic pressure and acceleration from which acoustic velocity is obtained. Potential and kinetic energies of underwater noise from two ship sources, computed in decidecimal bands centered between 25–630 Hz, are equal within calibration uncertainty of ±1.5 dB, representing a practical result towards the inference of kinematic properties from pressure-only measurements. Bivariate signals limited to two acoustic velocity components are placed in the context of the Stokes framework to describe polarization properties, such as the degree of polarization, which represents a statistical measure of the dispersion of the polarization properties. A bivariate signal composed of vertical and radial velocity components within a narrow frequency band centered at 63 Hz representing different measures of circularity and degree of polarization is examined in detail, which clearly demonstrates properties of bivariate signal trajectory. An examination of the bivariate signal composed of the two horizontal components of velocity within decidecimal bands centered at 63 Hz and 250 Hz demonstrates the importance of the degree of polarization in bearing estimation of moving sources.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-07T02:45:57Z
       
  • Dynamic sound absorption characteristics of a series piezoelectric
           acoustic absorber regulated by voltage

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      Authors: He Xu, Deyi Kong
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3807-3817, June 2022.
      A piezoelectric acoustic absorber composed of double micro-perforated panels (MPPs) and their back cavity is studied in this paper. The outer layer of the MPP absorber is a common metal MPP, and the inner layer is a piezoelectric MPP made of polyvinylidene fluoride (PVDF) film. When an alternating voltage is applied to the polyvinylidene fluoride (PVDF)-micro-perforated panel (MPP), it can be excited to generate different structural vibration modes, which can bring an additional absorption peak to the absorption performance curve of the piezoelectric acoustic absorber. The numerical simulation and experimental results indicate that the frequency and sound absorption coefficient of the additional sound absorption peak are closely related to the voltage parameters. Especially when the frequency of the alternating voltage is close to the eigen-frequency of PVDF-MPP, the additional sound absorption peak is more significant. Therefore, the absorption coefficient of the piezoelectric acoustic absorber at the corresponding frequency can be effectively enhanced by appropriately adjusting the parameters of the excitation voltage. This method of selectively and specifically improving the sound absorption performance of the required frequency band is very effective in reducing the noise in the dynamic change.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-07T02:45:56Z
       
  • Sonic boom reflection over an isolated building and multiple buildings

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      Authors: Didier Dragna, Ariane Emmanuelli, Sébastien Ollivier, Philippe Blanc-Benon
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3792-3806, June 2022.
      Sonic boom reflection is investigated over an isolated building and multiple buildings using numerical simulations. For that, the two-dimensional Euler equations are solved using high-order finite-difference techniques. Three urban geometries are considered for two boom waves, a classical N-wave and a low-boom wave. First, the variations of the pressure waveforms and the corresponding perceived noise are analyzed along an isolated building. The influence of the building is limited to an illuminated region at its front and a shadow region at its rear, whose size depends on the building's height and the Mach number. Two buildings are then considered. In addition to arrivals related to reflection on the building facades or to diffraction at the building corners, low-frequency oscillations, associated with resonances, are noticed in the street canyon. Their amplitude depends on the street width and on the incident boom frequency contents. Despite their significance, these low-frequency oscillations have little impact on the perceived noise. Finally, a periodic distribution of identical buildings is examined. The duration of the waveforms is notably increased due to multiple diffraction and canyon resonances. Variations in perceived noise at ground level are moderate for large streets, but become noticeable as the street width reduces.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-07T02:45:34Z
       
  • Influence of thermal deformations on sound absorption of three-dimensional
           printed metamaterials

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      Authors: Matteo Cingolani, Gioia Fusaro, Giulia Fratoni, Massimo Garai
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3770-3779, June 2022.
      Acoustic metamaterials (AMMs) are designed with complex geometrical shapes to obtain unconventional sound-absorbing performances. As additive manufacturing is particularly suited to print complex structures in a more straightforward and controllable way, AMMs often exploit three-dimensional (3-D) printing techniques. However, when exposed to different temperature conditions, such structures can be affected by geometrical deformations, especially when they are polymer-based. This can cause a mismatch between the experimental data and the expected theoretical performance; therefore, it is important to take thermal effects into account. The present paper investigates the influence of thermal deformations on the sound absorption of three geometries: a coplanar spiral tube, a system with double coiled resonators, and a neck-embedded resonator. Measurements were performed on each 3-D printed specimen in the impedance tube after the samples had been placed in a climate chamber to modify the temperature settings (T = 10–50 °C). Numerical models, validated on the measurements, were employed to quantify the geometrical deformation of AMM structures through a multiphysics approach, highlighting the effects of thermal stress on the acoustic behavior. The main outcomes prove that the frequency shifts of sound absorption peaks depend on temperature configurations and follow exponential regressions, in accordance with previous literature on polymeric materials.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-06T01:30:56Z
       
  • An automated piecewise synthesis method for cetacean tonal sounds based on
           time-frequency spectrogram

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      Authors: Zhongbo Sun, Jiajia Jiang, Yao Li, Chunyue Li, Zhuochen Li, Xiao Fu, Fajie Duan
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3758-3769, June 2022.
      Bionic signal waveform design plays an important role in biological research, as well as bionic underwater acoustic detection and communication. Most conventional methods cannot construct high-similarity bionic waveforms to match complex cetacean sounds or easily modify the time-frequency structure of the synthesized bionic signals. In our previous work, we proposed a synthesis and modification method for cetacean tonal sounds, but it requires a lot of manpower to construct each bionic signal segment to match the tonal sound contour. To solve these problems, an automated piecewise synthesis method is proposed. First, based on the time-frequency spectrogram of each tonal sound, the fundamental contour and each harmonic contour of the tonal sound is automatically recognized and extracted. Then, based on the extracted contours, four sub power frequency modulation bionic signal models are combined to match cetacean sound contours. Finally, combining the envelopes of the fundamental frequency and each harmonic, the synthesized bionic signal is obtained. Experimental results show that the Pearson correlation coefficient (PCC) between all true cetacean sounds and their corresponding bionic signals are higher than 0.95, demonstrating that the proposed method can automatically imitate all kinds of simple and complex cetacean tonal sounds with high similarity.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-06T01:30:55Z
       
  • Subspace-constrained deconvolution of auditory evoked potentials

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      Authors: Angel de la Torre, Joaquin T. Valderrama, Jose C. Segura, Isaac M. Alvarez, Jesus Garcia-Miranda
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3745-3757, June 2022.
      Auditory evoked potentials can be estimated by synchronous averaging when the responses to the individual stimuli are not overlapped. However, when the response duration exceeds the inter-stimulus interval, a deconvolution procedure is necessary to obtain the transient response. The iterative randomized stimulation and averaging and the equivalent randomized stimulation with least squares deconvolution have been proven to be flexible and efficient methods for deconvolving the evoked potentials, with minimum restrictions in the design of stimulation sequences. Recently, a latency-dependent filtering and down-sampling (LDFDS) methodology was proposed for optimal filtering and dimensionality reduction, which is particularly useful when the evoked potentials involve the complete auditory pathway response (i.e., from the cochlea to the auditory cortex). In this case, the number of samples required to accurately represent the evoked potentials can be reduced from several thousand (with conventional sampling) to around 120. In this article, we propose to perform the deconvolution in the reduced representation space defined by LDFDS and present the mathematical foundation of the subspace-constrained deconvolution. Under the assumption that the evoked response is appropriately represented in the reduced representation space, the proposed deconvolution provides an optimal least squares estimation of the evoked response. Additionally, the dimensionality reduction provides a substantial reduction of the computational cost associated with the deconvolution. matlab/Octave code implementing the proposed procedures is included as supplementary material.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-03T12:29:14Z
       
  • The impact of head-related impulse response delay treatment strategy on
           psychoacoustic cue reconstruction errors from virtual loudspeaker arrays

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      Authors: Matthew T. Neal, Pavel Zahorik
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3729-3744, June 2022.
      Known errors exist in loudspeaker array processing techniques, often degrading source localization and timbre. The goal of the present study was to use virtual loudspeaker arrays to investigate how treatment of the interaural time delay (ITD) cue from each loudspeaker impacts these errors. Virtual loudspeaker arrays rendered over headphones using head-related impulse responses (HRIRs) allow flexible control of array size. Here, three HRIR delay treatment strategies were evaluated using minimum-phase loudspeaker HRIRs: reapplying the original HRIR delays, applying the relative ITD to the contralateral ear, or separately applying the HRIR delays prior to virtual array processing. Seven array sizes were simulated, and panning techniques were used to estimate HRIRs from 3000 directions using higher-order Ambisonics, vector-base amplitude panning, and the closest loudspeaker technique. Compared to a traditional, physical array, the prior HRIR delay treatment strategy produced similar errors with a 95% reduction in the required array size. When compared to direct spherical harmonic (SH) fitting of head-related transfer functions (HRTFs), the prior delays strategy reduced errors in reconstruction accuracy of timbral and directional psychoacoustic cues. This result suggests that delay optimization can greatly reduce the number of virtual loudspeakers required for accurate rendering of acoustic scenes without SH-based HRTF representation.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-03T12:29:12Z
       
  • Auditory detection probability of propeller noise in hover flight in
           presence of ambient soundscape

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      Authors: Oksana Stalnov, Michael Faran, Yonatan Koral, Miriam Furst
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3719-3728, June 2022.
      Unmanned aerial vehicles are rapidly advancing and becoming ubiquitous in an unlimited number of applications, from parcel delivery to people transportation. As unmanned aerial vehicle (UAV) markets expand, the increased acoustic nuisance on population becomes a more acute problem. Previous aircraft noise assessments have highlighted the necessity of a psychoacoustic metric for quantification of human audio perception. This study presents a framework for estimating propeller-based UAV auditory detection probability on the ground for a listener in a real-life scenario. The detection probability is derived by using its free-field measured acoustic background and estimating the UAV threshold according to a physiological model of the auditory pathway. The method is presented via results of an exemplar measurement in an anechoic environment with a single two- and five-bladed propeller. It was found that the auditory detection probability is primarily affected by the background noise level, whereas the number of blades is a less significant parameter. The significance of the proposed method lies in providing a quantitative evaluation of auditory detection probability of the UAV on the ground in the presence of a given soundscape. The results of this work are of practical significance since the method can aid anyone who plans a hovering flight mode.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-03T12:29:11Z
       
  • Influence of meteorological conditions and topography on the active space
           of mountain birds assessed by a wave-based sound propagation model

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      Authors: Arthur Guibard, Frédéric Sèbe, Didier Dragna, Sébastien Ollivier
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3703-3718, June 2022.
      The active space is a central bioacoustic concept to understand communication networks and animal behavior. Propagation of biological acoustic signals has often been studied in homogeneous environments using an idealized circular active space representation, but few studies have assessed the variations of the active space due to environment heterogeneities and transmitter position. To study these variations for mountain birds like the rock ptarmigan, we developed a sound propagation model based on the parabolic equation method that accounts for the topography, the ground effects, and the meteorological conditions. The comparison of numerical simulations with measurements performed during an experimental campaign in the French Alps confirms the capacity of the model to accurately predict sound levels. We then use this model to show how mountain conditions affect surface and shape of active spaces, with topography being the most significant factor. Our data reveal that singing during display flights is a good strategy to adopt for a transmitter to expand its active space in such an environment. Overall, our study brings new perspectives to investigate the spatiotemporal dynamics of communication networks.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-03T12:29:09Z
       
  • Finite-element-based resonant ultrasound spectroscopy for measurement of
           multi-material samples

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      Authors: Paul R. Geimer, T. J. Ulrich, Luke B. Beardslee, Mathew L. Hayne, Marcel C. Remillieux, Tarik A. Saleh, Franz J. Freibert
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3633-3640, June 2022.
      Understanding the elastic properties of materials is critical for their safe incorporation and predictable performance. Current methods of bulk elastic characterization often have notable limitations for in situ structural applications, with usage restricted to simple geometries and material distributions. To address these existing issues, this study sought to expand the capabilities of resonant ultrasound spectroscopy (RUS), an established nondestructive evaluation method, to include the characterization of isotropic multi-material samples. In this work, finite-element-based RUS analysis consisted of numerical simulations and experimental testing of composite samples comprised of material pairs with varying elasticity and density contrasts. Utilizing genetic algorithm inversion and mode matching, our results demonstrate that elastic properties of multi-material samples can be reliably identified within several percent of known or nominal values using a minimum number of identified resonance modes, given sample mass is held consistent. The accurate recovery of material properties for composite samples of varying material similarity and geometry expands the pool of viable samples for RUS and advances the method towards in situ inspection and evaluation.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:44Z
       
  • Numerical investigation of rod–airfoil interaction noise reduction
           using cylindrical collars

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      Authors: Chenghao Yang, Heying Feng, Yehui Peng, Fan Tong, Nvzi Bao
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3641-3653, June 2022.
      Noise reduction by collars applied to rod–airfoil was studied numerically. The flow field and acoustic far-field are predicted using a large eddy simulation and the Ffowcs Williams and Hawking acoustic analogy. The present numerical method is first validated by existing experimental and numerical results for the baseline case. Then, to reduce interaction noise, a rod with collars is designed (denoted as the Col case). The main noise reduction mechanisms of the collars are investigated in detail. The numerical results show that the collars reduce the noise in the low- and medium-frequency bands of the rod, for which the tonal noise is reduced by 24.83 dB. The airfoil noise throughout the frequency band is thereby reduced as the main sound source. The upstream wake is regularized, and vortex shedding is suppressed. The surface pressure fluctuations along the rod, leading edge, and trailing edge of airfoil exhibit an obvious attenuation in the Col case compared with the baseline, which leads to a decrease in the sound source strength. It is also found that there exist spanwise decorrelation and decoherence effects along the rod with collars, which means the evolution of the turbulent vortices is regularized and the physical size of eddies is minified.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:43Z
       
  • Temperature-controlled spatiotemporally modulated phononic crystal for
           achieving nonreciprocal acoustic wave propagation

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      Authors: Justin Palacios, Lazaro Calderin, Allan Chon, Ian Frankel, Jihad Alqasimi, Florian Allein, Rachel Gorelik, Trevor Lata, Richard Curradi, Gabrielle Lambert-Milak, Anuja Oke, Neale Smith, Maroun Abi Ghanem, Pierre Lucas, Nicholas Boechler, Pierre Deymier
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3669-3675, June 2022.
      We computationally investigate a method for spatiotemporally modulating a material's elastic properties, leveraging thermal dependence of elastic moduli, with the goal of inducing nonreciprocal propagation of acoustic waves. Acoustic wave propagation in an aluminum thin film subjected to spatiotemporal boundary heating from one side and constant cooling from the other side was simulated via the finite element method. Material property modulation patterns induced by the asymmetric boundary heating are found to be non-homogenous with depth. Despite these inhomogeneities, it will be shown that such thermoelasticity can still be used to achieve nonreciprocal acoustic wave propagation.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:42Z
       
  • Diffuse ultrasound computed tomography

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      Authors: Ines Elisa Ulrich, Christian Boehm, Andrea Zunino, Cyrill Bösch, Andreas Fichtner
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3654-3668, June 2022.
      An alternative approach to acquire transmission travel time data is proposed, exploiting the geometry of devices commonly used in ultrasound computed tomography for medical imaging or non-destructive testing with ultrasonic waves. The intent is to (i) shorten acquisition time for devices with a large number of emitters, (ii) to eliminate the calibration step, and (iii) to suppress instrument noise. Inspired by seismic ambient field interferometry, the method rests on the active excitation of diffuse ultrasonic wavefields and the extraction of deterministic travel time information by inter-station correlation. To reduce stochastic errors and accelerate convergence, ensemble interferograms are obtained by phase-weighted stacking of observed and computed correlograms, generated with identical realizations of random sources. Mimicking an imaging setup, the accuracy of the travel time measurements as a function of the number of emitters and random realizations can be assessed both analytically and with spectral-element simulations for phantoms mimicking the model parameter distribution. The results warrant tomographic reconstructions with straight- or bent-ray approaches, where the effect of inherent stochastic fluctuations can be made significantly smaller than the effect of subjective choices on regularisation. This work constitutes a first conceptual study and a necessary prelude to future implementations.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:41Z
       
  • A method to convert neural signals into sound sequences

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      Authors: Alain Destexhe, Luc Foubert
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3685-3689, June 2022.
      We present a method to convert neural signals into sound sequences, with the constraint that the sound sequences precisely reflect the sequences of events in the neural signal. The method consists in quantifying the wave motifs in the signal and using these parameters to generate sound envelopes. We illustrate the procedure for sleep delta waves in the human electro-encephalogram (EEG), which are converted into sound sequences that encode the time structure of the original EEG waves. This procedure can be applied to synthesize personalized sound sequences specific to the EEG of a given subject.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:40Z
       
  • An ultrasonically actuated fine-needle creates cavitation in bovine liver

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      Authors: Emanuele Perra, Nick Hayward, Kenneth P. H. Pritzker, Heikki J. Nieminen
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3690-3702, June 2022.
      Ultrasonic cavitation is being used in medical applications as a way to influence matter, such as tissue or drug vehicles, on a micro-scale. Oscillating or collapsing cavitation bubbles provide transient mechanical force fields, which can, e.g., fractionate soft tissue or even disintegrate solid objects, such as calculi. Our recent study demonstrates that an ultrasonically actuated medical needle can create cavitation phenomena inside water. However, the presence and behavior of cavitation and related bioeffects in diagnostic and therapeutic applications with ultrasonically actuated needles are not known. Using simulations, we demonstrate numerically and experimentally the cavitation phenomena near ultrasonically actuated needles. We define the cavitation onset within a liver tissue model with different total acoustic power levels. We directly visualize and quantitatively characterize cavitation events generated by the ultrasonic needle in thin fresh bovine liver sections enabled by high-speed imaging. On a qualitative basis, the numerical and experimental results show a close resemblance in threshold and spatial distribution of cavitation. These findings are crucial for developing new methods and technologies employing ultrasonically actuated fine needles, such as ultrasound-enhanced fine-needle biopsy, drug delivery, and histotripsy.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:39Z
       
  • Green's functions for a layered high-contrast acoustic media

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      Authors: Özgür Özdemir, Hazel Yücel, Yaǧmur Ece Uçar, Bariş Erbaş, Nihal Ege
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3676-3684, June 2022.
      A parametric approach based on parametric analysis of the acoustical properties of a layered media is proposed to derive a reduced layered Green's function. The approach relies on the smallness of one of the problem parameters and allows a simpler form of Green's function by disregarding the smaller parametric terms. Several illustrative examples comparing the amplitudes of exact and reduced Green's function for small parameter of density ratio in various source and observation location setups are presented. It is demonstrated that the CPU times calculated at different points decrease considerably for the reduced Green's function, further justifying the presented method.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-02T11:29:39Z
       
  • Subwavelength Su-Schrieffer-Heeger topological modes in acoustic
           waveguides

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      Authors: Antonin Coutant, Vassos Achilleos, Olivier Richoux, Georgios Theocharis, Vincent Pagneux
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3626-3632, June 2022.
      Topological systems furnish a powerful way of localizing wave energy at edges of a structured material. Usually, this relies on Bragg scattering to obtain bandgaps with nontrivial topological structures. However, this limits their applicability to low frequencies because that would require very large structures. A standard approach to address the problem is to add resonating elements inside the material to open gaps in the subwavelength regime. Unfortunately, generally, one has no precise control on the properties of the obtained topological modes, such as their frequency or localization length. In this work, a unique construction is proposed to couple acoustic resonators such that acoustic modes are mapped exactly to the eigenmodes of the Su-Schrieffer-Heeger (SSH) model. The relation between energy in the lattice model and the acoustic frequency is controlled by the characteristics of the resonators. In this way, SSH topological modes are obtained at any given frequency, for instance, in the subwavelength regime. The construction is also generalized to obtain well-controlled topological edge modes in alternative tunable configurations.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:54Z
       
  • Nonlinear characteristics of high amplitude focusing using time reversal
           in a reverberation chamber

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      Authors: Brian D. Patchett, Brian E. Anderson
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3603-3614, June 2022.
      Time reversal (TR) signal processing is an effective tool to exploit a reverberant environment for the intentional focusing of airborne, audible sound. A previous room acoustics TR study found preliminary evidence that above a certain focal amplitude the focal waveform begins to display signs of nonlinearity [Willardson, Anderson, Young, Denison, and Patchett, J. Acoust. Soc. Am. 143(2), 696–705 (2018)]. This study investigates that nonlinearity further by increasing the focal peak amplitudes beyond that previously observed. This increases the nonlinear characteristics, allowing for a closer inspection of their properties. An experiment is conducted using eight horn loudspeaker sources and a single receiver in a reverberation chamber. A maximum peak focal amplitude of 214.8 kPa (200.6 dBpk) is achieved. The focus signal waveforms are linearly scaled to observe and characterize the nonlinear amplification of the waveform. Frequency spectra of the peak focal amplitudes are plotted to observe changes in frequency content as the signals become nonlinear. A one-dimensional spatial scan of the focal region is conducted to observe properties of the converging and diverging waves. A proposal for a possible explanation involving free-space Mach stem formation is given.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:51Z
       
  • Investigation on whistle directivity in the Indo-Pacific humpback dolphin
           (Sousa chinensis) through numerical modeling

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      Authors: Zhongchang Song, Chuang Zhang, Weijie Fu, Zhanyuan Gao, Wenzhan Ou, Jinhu Zhang, Yu Zhang
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3573-3579, June 2022.
      Odontocetes have evolved special acoustic structures in the forehead to modulate echolocation and communication signals into directional beams to facilitate feeding and social behaviors. Whistle directivity was addressed for the Indo-Pacific humpback dolphin (Sousa chinensis) by developing numerical models in the current paper. Directivity was first examined at the fundamental frequency 5 kHz, and simulations were then extended to the harmonics of 10, 15, 20, 25, and 30 kHz. At 5 kHz, the –3 dB beam widths in the vertical and horizontal planes were 149.3° and 119.4°, corresponding to the directivity indexes (DIs) of 4.4 and 5.4 dB, respectively. More importantly, we incorporated directivity of the fundamental frequency and harmonics to produce an overall beam, resulting in −3 dB beam widths of 77.2° and 62.9° and DIs of 8.2 and 9.7 dB in the vertical and horizontal planes, respectively. Harmonics can enhance the directivity of fundamental frequency by 3.8 and 4.3 dB, respectively. These results suggested the transmission system can modulate whistles into directional projection, and harmonics can improve DI.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:49Z
       
  • Equivalent circuit for analyzing the transmitting characteristics of
           multimode Tonpilz transducer

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      Authors: Seonghun Pyo, Yongrae Roh
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3594-3602, June 2022.
      Multimode Tonpilz transducers operate at longitudinal and flexural vibration modes simultaneously. Consequently, they have wider bandwidths than conventional single-mode transducers. Generally, the performance of Tonpilz transducers is analyzed using the finite element method (FEM), whereas the equivalent circuit method (ECM) has proven to be a fast and efficient alternative to the FEM. However, the ECM for analyzing the acoustic characteristics of multimode Tonpilz transducers has not yet been developed. To address this issue, an equivalent circuit for the multimode Tonpilz transducer is developed herein. The proposed ECM encompasses the flexural characteristics of the Tonpilz head mass, which is impossible with conventional equivalent circuits. Furthermore, a prototype of the multimode Tonpilz transducer was fabricated to verify the validity of the developed ECM. Additionally, the accuracy and compliance of the ECM were confirmed by comparing the measured performance of the transducer with that from the equivalent circuit analysis.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:48Z
       
  • Numerical prediction of loudness metrics for N-waves and shaped sonic
           booms in kinematic turbulence

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      Authors: Alexander N. Carr, Joel B. Lonzaga, Steven A. E. Miller
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3580-3593, June 2022.
      The effects of a kinematic field of velocity fluctuations on the loudness metrics of two waveforms are examined with a three-dimensional one-way propagation solver. The waveforms consist of an N-wave and a simulated low-boom from NASA's X-59 QueSST aircraft. The kinematic turbulence is generated using a von Kármán composite spectrum, which is dependent on a root mean square (rms) velocity and outer scale of the turbulence. A length scale is proposed to account for the effect of the rms velocity and integral scale on the focusing and defocusing of the sonic boom waveform. The probability density function of the location of the first caustic attains a maximum value when the propagation distance is equal to the proposed length scale. Simulation results indicate that for small values of the nondimensional propagation distance, the standard deviation of the loudness metrics increases linearly. The loudness metrics follow a normal distribution within a given range of the nondimensional propagation distance. Results indicate the potential to parameterize the loudness metric distributions by the rms velocity and integral length scale.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:46Z
       
  • Rigorous analysis of the axial acoustic radiation force on a spherical
           object for single-beam acoustic tweezing applications

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      Authors: Bart P. Weekers, Xavier Rottenberg, Liesbet Lagae, Veronique Rochus
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3615-3625, June 2022.
      Acoustic tweezers are increasingly utilized for the contactless manipulation of small particles. This paper provides a theoretical model demonstrating the acoustic manipulation capabilities of single-beam acoustic transducers. Analytical formulas are derived for the acoustic radiation force on an isotropic spherical object of arbitrary size, centered on a circular piston, simply supported and clamped radiator in an inviscid fluid. Using these results, the existence of a negative axial force pulling the object closer to the radiator is revealed and explored. These findings offer further insight into the feasibility of trapping objects in the near-field of a single-beam acoustic transducer. The calculations illustrate the trapping capabilities of the different emitters as a function of radiator size, particle size, and distance from the source and highlight the impact of radiator boundary conditions. Manipulation of a cell-like fluid sphere in water and an expanded polystyrene sphere in air are studied in more detail with results that are validated through finite element analysis. The developed theoretical model allows fast evaluation of acoustic radiation forces which could aid in the development of relatively simple and inexpensive contactless manipulation solutions.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:44Z
       
  • Reviews of Acoustical Patents

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      Authors: Sean A. Fulop
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page 3565-3572, June 2022.
      The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Patents are available via the internet at the USPTO website.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:43Z
       
  • R. L. Pritchard's classic mutual impedance contribution

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      Authors: John L. Butler
      Abstract: The Journal of the Acoustical Society of America, Volume 151, Issue 6, Page R13-R14, June 2022.
      The Reflections series takes a look back on historical articles from The Journal of the Acoustical Society of America that have had a significant impact on the science and practice of acoustics.
      Citation: The Journal of the Acoustical Society of America
      PubDate: 2022-06-01T12:42:40Z
       
 
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