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Acoustics Australia
Journal Prestige (SJR): 0.232  Citation Impact (citeScore): 1 Number of Followers: 1  Hybrid journal (It can contain Open Access articles)ISSN (Print) 0814-6039 - ISSN (Online) 1839-2571 Published by Springer-Verlag  [2467 journals]
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- Numerical and Experimental Investigations of Multiple Resonators on
Reducing Tyre Cavity Resonance Noise-
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Abstract: Abstract Tyre cavity resonance noise is one kind of low-frequency and narrow-band noise that particularly affects the passengers inside the cabin of vehicle, especially when driving at a medium speed. In this paper, a noise reduction structure made of multiple resonators is proposed to reduce this type of noise. Based on the local resonance principle, the dimension of the resonator unit is determined by the tyre cavity resonance frequency. In order to obtain this characteristic frequency and the acoustic feature, the acoustic-structure coupling model of the tyre and cavity is established by the finite element method (FEM), and the modal frequency and shape of the tyre cavity are calculated and validated by the experimental results. Based on these analyses, the geometric and material parameters of the sound reduction structure are calculated to match the resonant frequency of the tyre cavity. A long belt filled with multiple resonators is designed to fit the profile of the tyre cavity, and simulations and experimental tests are conducted to investigate the noise reduction performance. The results show that the multiple resonators can significantly reduce the sound pressure inside the tyre cavity due to the vibroacoustic coupling effect. This paper provides a novel solution for reducing tyre cavity resonance noise.
PubDate: 2023-03-24
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- The Effect of Classroom Acoustic Treatment on Listening, Learning, and
Well-being: A Scoping Review-
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Abstract: Abstract Classrooms are important learning spaces, however, the acoustic conditions in these spaces can often be suboptimal. The aim of this scoping review, which used the PRISMA-ScR protocol, was to understand what is known from the literature about the effect of classroom acoustic treatment on students’ listening, learning, and well-being. Thirteen papers from the database searches were deemed relevant for the review. Information on the years of publication of the papers, the population studied, the types of acoustic treatment used, the measures and methods used to assess the effect of acoustic treatment, and the outcomes of the papers was gathered. Seven of the 13 studies reported positive effects of classroom acoustic treatment on student’s speech perception, attention, and well-being. Five studies reported both positive effects and no effect depending on the measure, condition, or population. The remaining study reported a negative effect of classroom acoustic treatment on children’s speech perception and listening effort. These findings suggest that the effect of ceiling and/or wall absorbers/diffusers on sound and reverberation in the room can help students’ speech perception, attention, reading, and well-being, but they may also reduce the speech transmission index resulting in increased listening effort. The limitations of the reviewed studies and avenues for future research on the effect of acoustic treatment on a broader range of listening, learning, and well-being outcomes for students are discussed.
PubDate: 2023-03-24
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- A Modified Reference Signal Selection Method for Feed-Forward Active Road
Noise Control System-
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Abstract: Abstract Active control of road noise has been widely recognized as a promising technology. For a feed-forward active road noise control system, the proper selection of the reference vibration signals is very important. It determines the theoretically optimal effect that the system can achieve. In order to achieve a reasonable selection of reference signals, a modified signal selection method is proposed in this paper. A test on road noise data acquisition and relevant analysis is conducted to decide the target frequency band for noise control. After that, an initial reference signal set is established and it is expanded by iteratively calculating the Fisher information matrix and the amount of new correlation information so that a reference signal set that has optimal multiple coherence with road noise is obtained. In the case study, a comparison between the traditional method and the proposed method is conducted. The results show that the proposed method can reach a higher average coherence coefficient and better noise reduction performance than the traditional method.
PubDate: 2023-03-14
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- Study on the Performance Improvement Mechanisms of Expansion Chamber Water
Mufflers with Reacting End Walls-
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Abstract: Abstract This paper investigated the effect of wall compliance on the noise attenuation performance of a water muffler. Firstly, the sound transmission loss (TL) of an expansion chamber with a piston-spring element located at one end wall of the chamber was derived using the transfer matrix method. It is found that transmission loss of a water-filled expansion chamber can be noticeably improved by introducing a reacting element, especially for the low-frequency range and frequency range around the resonance of the reacting element. A further lumped model established using acoustical–electrical analogy reveals that the reacting element functions as a volume amplifier of the expansion chamber for the low-frequency range, while the resonant behavior is dominated by the area and impedance of the reacting element. Then, the model was extended by replacing the piston-spring element with a circular plate. A 1.5-dimensional model was developed in which the fluid–structure interaction was regarded as an added mass effect, and a FEM model was used to verify the accuracy of the theoretical model. Finally, the effects of material properties, thickness, radius, boundary conditions, surface area, and length of the expansion chamber on the sound attenuation performance of reacting expansion chamber mufflers have been examined and discussed.
PubDate: 2023-03-09
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- Numerical Evaluation of the Human Skull with Focused Ultrasound
Stimulation-
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Abstract: Abstract Transcranial focused ultrasound stimulation is a promising brain stimulation technique for its noninvasiveness and higher spatial resolutions and is used for various neuromodulation applications. As the skull is the primary barrier to delivering ultrasound to the deep brain region, it induces unpredictable ultrasound exposure. The objective of the study is to design customised transducers and assess the effects of the skull on ultrasound wave propagation. Computational skull models were constructed using computerised tomography scans. A full-wave finite-difference time-domain simulation platform, Sim4Life, was then used to design and simulate ultrasound wave propagation. In addition, the impacts of the skull were assessed through sensitivity analysis in the intracranial intensity, pressure, full width at half maximum, and energy deposition. Compared to the intracranial intensity distribution when the transducer is placed over the top area of the skull, the peak intensity increased by 23.4% for transmission through the temporal window. The temporal window, the thinnest part of the skull, provides a site for intracranial peak intensity and optimal focal spot area using focused ultrasound. The numerical investigation in this study provided a guideline for targeting and dosing, accounting for and lessening variability in studies addressing transcranial focused ultrasound applications.
PubDate: 2023-02-25
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- Robust Matched Field Processing Using an Empirical Characteristic Function
Approach Under Impulsive Noise Environments-
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Abstract: Abstract Matched Field Processing (MFP) is an inversion technique often employed in source localization applications. Conventional MFP approaches are incapable of producing precise results in the presence of extremely impulsive noises, which are typically present in actual applications such as underwater acoustics. This is because the covariance matrix for this category of noises does not converge. Moreover, impulsive noise suppression algorithms fail to provide accurate results. Particularly, fractional lower order moment (FLOM)-based approaches have an unbounded output, and data trimming methods introduce uncertainty into the estimation covariance matrix. In this study, a novel MFP method employing the empirical characteristic function (ECF) is developed. The desirable properties of the characteristic function (CF) result in a robust localization method that is ideally suited for extremely strong tailed noise environments. Using the CF array output, a new covariance-like matrix that can be used in MFP methods has been constructed. To demonstrate the efficiency of the ECF-MFP technique, experiments are conducted in a water tank. Experimental results reveal that this method is very robust in the presence of very heavy tailed noise, a low signal-to-noise ratio, and a tiny sample size. Additionally, it outperforms previous approaches in terms of resolution probability.
PubDate: 2023-02-25
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- Evaluation of the Speech Intelligibility of the Ear of Dionysius in
Syracuse-
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Abstract: Abstract The Ear of Dionysius cavern has frequently been explored for its unique acoustic properties. According to legend, it amplifies whispers and soft sounds so that they can be heard through a narrow tunnel 35 m above the ground. The legend refers to Dionysius, who ruled Syracuse between 432 and 376 BC and was supposedly able to hear the whispered secrets of prisoners chained in the cave. Acoustic measurements, simulations, and intelligibility listening tests were conducted to investigate the validity of this legend. The results were analyzed and compared to evaluate the definition (D50) and speech transmission index at different locations in the cave. The results show that speech intelligibility in the Ear of Dionysius cavern is rated “fair” overall according to the ISO 9921 criteria, with better values in the central zone of the space. This fair rating suggests that the legend of the tyrant Dionysius eavesdropping on prisoners’ conversations may not be based in reality.
PubDate: 2023-01-16
DOI: 10.1007/s40857-023-00286-9
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- Sonar Self-noise and Acoustic Transmission of Acoustic Window Made from
Functionally Gradient Materials-
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Abstract: Abstract The sonar self-noise characteristics of an acoustic window made from multilayer functionally gradient materials (FGMs) under external turbulent pulsating pressure excitation were theoretically modeled using the multilayer plate (MLP) transfer function method and the turbulent pulsating pressure wavenumber–frequency spectrum. An MLP transfer matrix was used to determine acoustic transmission loss of the multilayer FGM plate under plane wave excitation. The theoretical model was verified by the finite element method. The FGM was fabricated from rubber and fiberglass-reinforced plastics (FRP)/carbon fiber. The acoustical transmission loss of the multilayer FGM plate and noise reduction patterns of the multilayer FGM acoustic windows were assessed at different gradients. The acoustic effect of the window on external sound waves and its spatial filtering effect on external turbulent fluctuation excitations can be adjusted by regulating the proportions of rubber and FRP, which changes the gradient variation pattern.
PubDate: 2022-12-05
DOI: 10.1007/s40857-022-00283-4
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- A Scoping Review of the Effect of Classroom Acoustic Conditions on Primary
School Children’s Numeracy Performance and Listening Comprehension-
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Abstract: Abstract Obtaining adequate numeracy skills and listening comprehension skills at primary school are vital for children’s future success. However, classrooms are often noisy and reverberant which may interfere with learning these skills. Two scoping reviews were conducted to synthesise research assessing the effect of different classroom acoustic conditions on (1) children’s numeracy performance and (2) children’s listening comprehension and to identify areas for future research. The PRISMA-ScR protocol was used for these scoping reviews. A comprehensive search of four online databases was conducted in September 2021 using the search term classroom AND (noise OR reverberation OR acoustics) AND (numeracy OR math* OR arithmetic) for the first scoping review, and in May 2022 using the search term classroom AND (acoustic* OR noise OR reverb*) AND ("listening comprehension" OR "auditory comprehension" OR "spoken language comprehension" OR "speech comprehension”) for the second scoping review. The effect of the acoustic conditions on children’s numeracy was varied with most studies showing a negative or no effect of noise, but two showed a positive effect. Therefore, future research is needed to better understand the effect of different classroom acoustic conditions on children’s numeracy performance. For listening comprehension overall, signal-to-noise ratios below + 10 dB mostly had a negative effect on children’s listening comprehension compared to quiet conditions; however, variables such as the noise type, signal-to-noise ratio tested, the listening comprehension domain examined, the population studied, and the voice used for the stimuli affected this. Future research avenues to better understand these effects are proposed.
PubDate: 2022-11-16
DOI: 10.1007/s40857-022-00284-3
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- Small Sample Size and Experience-Independent Hydrate and Pipeline Leakage
Identification Technique for Natural Gas Pipelines Based on Deep Forest-
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Abstract: Abstract Hydrate blockage and pipeline leakage are two common factors that threaten the safety of natural gas pipelines. However, most of the current research focuses on nonintrusive, passive-like techniques that can only detect one of these abnormal events, with occasional attention to identification technique. This paper introduces an active method to simultaneously detect hydrate blockage and pipeline leakage using intrusive sensors, and further presents a deep forest-based classification method for two types of abnormal events, which aims to avoid the problem that the classification of traditional deep learning depends on huge number of hard-to-acquire samples. Besides, network structure and parameters in deep learning affect the classification performance, and deep forest is just a better solution to this problem. The parameter tuning experiments results of deep forest show that the classification accuracies are mostly 100% whatever in training and testing, proving that different parameter settings have little effect on the classification accuracy. The stability and portability of the classification method are tested, and it is verified that this classification method is easy to implement and has strong universality, which is expected to be applied to other types of natural gas pipeline event classification.
PubDate: 2022-11-10
DOI: 10.1007/s40857-022-00285-2
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- On the Applicability of Cold Acoustic Measurements to High-Amplitude Hot
Pulsating Flows-
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Abstract: Abstract The experimental characterization of the acoustic characteristics of engine exhaust devices is usually carried out through measurements in cold conditions, due to the intrinsic difficulties associated with proper temperature control in an acoustic rig. While those measurements may be sufficiently indicative for the cold end of the exhaust (the silencing elements) their significance for the hot end (the aftertreatment system) is more doubtful, as a result of the high temperatures and, eventually, the higher amplitude of pressure waves acting on the system. In this paper, a direct assessment is provided on the significance of acoustic measurements in cold conditions for representing the actual behaviour of an aftertreatment system in a hot pulsating, engine-like flow. Making use of wave decomposition techniques, the measured characterization was convoluted with the hot-flow excitation and the device responses were directly compared. The results indicate that, while it is not possible to fully reproduce the behaviour observed in hot pulsating flow, the tendencies are reproduced, at least qualitatively. In particular, the effect of soot loading is fairly reproduced.
PubDate: 2022-10-11
DOI: 10.1007/s40857-022-00282-5
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- Assessment of Two Audio-Recording Methods for Remote Collection of Vocal
Biomarkers Indicative of Tobacco Smoking Harm-
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Abstract: Abstract This study aimed to determine if self-complete at-home recordings could produce audio samples of sufficient quality for use in voice analysis software, and if audio samples of similar or sufficient quality could be extracted from audio-recorded naturalistic phone interviews. Data were obtained from 31 adults aged 18 years and over who smoked. The /a/ sound segment was manually isolated, and analysis functions were used to produce the following values: fundamental frequency, jitter, shimmer, noise ratio, formant 3, and formant 4. The /a/ sound segment was then manually isolated from audio recordings of naturalistic interviews previously conducted by phone. These were analysed in the same way and compared for quality against Evistr-recorded audio samples from the same participants. A third audio sample consisted of an Evistr or phone-recorded sustained phonation of the /a/ sound. Means and standard deviations were calculated for the target vocal parameters. Statistical comparisons for quality of sound segment were conducted for readings, interviews, and vowel phonation and for sound signals extracted via both recording methods. Self-recording by adults who smoked provided audio samples of sufficient quality for analysis of vocal features that have been associated with a clinical outcome. The values obtained for sustained phonation audio samples displayed the least perturbation and noise for the vocal parameters surveyed. Sound signals recorded with smartphones appeared to be affected by electronic interference but have potential for use in diagnostic tools for measuring vocal parameters.
PubDate: 2022-09-26
DOI: 10.1007/s40857-022-00279-0
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- Numerical and Experimental Study of the Effect of the Bridge of Sarasvati
Veena on its Timbre-
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Abstract: Abstract The Sarasvati Veena is an Indian stringed musical instrument with a curved bridge having a parabolic equation. We study the effect of such a bridge on the timbre of the instrument. We model the interaction of the vibrating string with the bridge as frictionless impact. So we implemented an energy-conserving method where string–bridge interaction is modelled with a penalty approach. We solve the resulting Hamilton’s equations numerically. Simulations are performed with different values of bridge parameters, namely slope and curvature. The numerical model is validated by comparison with experimental analysis. We isolate the contribution of the bridge by mounting it on the sonometer in place of one of its knife-edges and a mechanism is provided on the sonometer to change the bridge slope. We mounted the sonometer on foam to minimize the effect of other structural parameters. The typical Veena timbre shows sustain of most harmonics and the revival of higher harmonics with time. These features are attributed to the shape of the metallic layer at the top of the Veena bridge, its slope and curvature. Our model also shows these features, which are further corroborated by the experiment.
PubDate: 2022-09-19
DOI: 10.1007/s40857-022-00280-7
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- Mechanical and Acoustic Properties of Ceramsite Sound Absorbing Boards
with Gradient Structure-
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Abstract: Abstract In this work, ceramsite was utilized to fabricate the sound-absorbing boards, in which two types of structure were considered, specifically, single-layer board with homogenous structure and double-layer board with gradient structure. The physical, mechanical and acoustic properties of these prepared ceramsite sound absorbing boards were studied, including the bulk density, compressive strength, flexural strength, softening coefficient, sound absorption coefficient and sound reduction index. The results show that the double-layer board with appropriate mixture design exhibited almost identical bulk density and mechanical strength to the single-layer board. All ceramsite sound absorbing boards had compressive and flexural strengths of more than 3 MPa and 1 MPa, respectively, and also demonstrated good water resistance. In terms of sound absorption and sound insulation properties, the overall performance of the double-layer board with reasonable gradient structure was better than that of the single-layer board. In addition, the physical structure models of ceramsite sound absorbing boards were established to illustrate the variation of mechanical properties and disclose the mechanism of sound absorption and insulation in the material.
PubDate: 2022-08-07
DOI: 10.1007/s40857-022-00276-3
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- Self-Powered Acoustic Sensor Based on Triboelectric Nanogenerator for
Smart Monitoring-
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Abstract: Abstract Sound as a ubiquitous energy in our surroundings is clean and sustainable, and carries abundant information in a wide frequency bandwidth. However, effectively harvesting and utilizing acoustic energy is still hindered by the limitations such as low energy density of acoustic energy and lack of novel application. In this paper, we successfully present a self-powered acoustic sensor, which is composed of an adjustable spacing structure and sound-driven triboelectric nanogenerator (TENG). The acoustic sensor exhibits excellent electric output properties because of the poriferous electrode structure, ultrathin vibrating membrane as well as high-quality triboelectric materials. The sensor can deliver a maximal output voltage of 6.28 V with the sound frequency of 350 Hz and sound pressure of 110 dB. In addition, the electric output frequency is closely related to the applied acoustic wave and the corresponding directional dependence pattern as a butterfly is highly symmetrical. Our approach presents a cost-effective strategy to develop self-powered acoustic sensor and shows great potentials in home automation, self-powered microphone, sensor network and artificial intelligence.
PubDate: 2022-08-05
DOI: 10.1007/s40857-022-00275-4
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- Whistle Variation in Indo-Pacific Humpback Dolphins (Sousa chinensis) in
Relation to Behavioural and Environmental Parameters in Northwestern
Peninsular Malaysia-
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Abstract: Abstract Dolphins have a diverse acoustic communication system which includes whistles necessary for their survival. Whistle variation in dolphins could be related to the group behaviour, group size, formation and also environmental factors such as water depth, tidal phases and location. Such information is relatively unknown for the dolphin populations in Malaysia. This study aims to understand the whistle variation in Indo-Pacific humpback dolphins found in two sites in northwestern Peninsular Malaysia and possible factors that influence their whistles. A total of 4971 whistles were detected with whistle rates and parameters analysed. A GLMM analysis showed that whistle rates in both sites and in differing group sizes had significant differences. Only the mean whistle frequency significantly differed in differing group formations. Indo-Pacific humpback dolphins in a loose and uniform group had a lower mean frequency compared to other group formations. Other parameters such as the whistle duration and coefficient of frequency modulation did not show significant differences in differing behaviour, size, formation, water depth, tidal phases and location. This study is important and particularly valuable for understanding the species’ bioacoustics in the wider region of Southeast Asia.
PubDate: 2022-07-19
DOI: 10.1007/s40857-022-00273-6
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- Optimization Design of Acoustic Performance of Underwater Anechoic
Coatings-
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Abstract: Abstract Acoustic coatings with periodically arranged internal cavities have been widely applied to underwater vessels to reduce the underwater sound scattering. In this study, the simulation results from the finite element method (FEM) have been compared with the theoretical solutions based on the transfer matrix theory (TMT), and the reliability of the FEM has been verified. The Nelder-Mead algorithm has been employed to optimize the structure of the coatings and the material parameters with the sound absorption coefficient as the primary optimization objective. A function that characterizes the shape of a two-dimensional axisymmetric cavity has been proposed, and the peak value of the absorption coefficient can be successfully moved to the target frequency by changing the weighting strategy. The results show that the sound absorption coefficient of the optimized coating increases and the peak shape widens in the middle and low frequency band. The optimized axisymmetric cavity significantly improves the sound absorption performance of the anechoic coatings. The optimization algorithm of the cavity structure and material parameters proposed in this study provide an effective pathway for the optimal design of the anechoic coatings.
PubDate: 2022-07-09
DOI: 10.1007/s40857-022-00267-4
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- External Acoustical Damping on a Metallic Angle Wedge in a High
Temperature Resistant Ultrasonic Probe-
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Abstract: Abstract Ultrasonic probes for high-temperature applications are provided with metallic wedges, which can withstand the contact with the high temperature of the inspected structure. The ultrasonic signal travels within the wedge and gets reflected from its boundaries, causing interference signals called “ghost echoes”. The current work presents an investigation of the additional damping effect provided by porous sintered metal plates applied onto the surface of the wedge. In particular, the study evaluates the effect of damping plate thickness on the interference signal level at different transmission frequencies. Damping plates made of sintered metal SIKA-R 15 AX were attached to a wedge prototype made of steel 1.4301. The study revealed, that the most effective thickness of damping plates in the selected frequency interval of 1 to 4 MHz is equal to 4 mm. The evaluation of the interference signal has shown that the application of such damping plates to the wedge surface contributes to an additional attenuation of an interference signal of 10 to 30 dB after 500 µs of signal propagation.
PubDate: 2022-07-08
DOI: 10.1007/s40857-022-00270-9
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- A Scoping Review of the Effects of Classroom Acoustic Conditions on
Primary School Children’s Physical Health-
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Abstract: Abstract The aim of this scoping review was to synthesize research assessing the effect of classroom acoustic conditions on children’s physical health and identify areas for future research. This scoping review followed the PRISMA-ScR protocol. A comprehensive search of four online databases (ERIC, PubMed, Scopus, and Web of Science) was conducted using the search term classroom AND (acoustic* OR noise OR reverb*) AND health. Peer-reviewed journal articles were included if they were written in English, included children in the primary school age range (i.e. 5–12 years), and included a measure of children’s physical health. Eight papers out of the 407 papers returned in the search met the criteria to be included in the review. The results were analysed according to the effect of traffic noise, aircraft noise, and internal classroom noise on children’s physical health. The results were somewhat mixed, but overall they suggest that noise may have a negative effect on children’s physical health by inducing a stress response that results in asthma, fatigue, and headaches. Future research avenues are proposed to better understand the relationship between classroom acoustic conditions and children’s physical health.
PubDate: 2022-07-08
DOI: 10.1007/s40857-022-00271-8
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- Application of Reciprocity to Calculating the Scattering Matrix of a
Complex Muffler Without and With Nonuniform Meanflow-
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Abstract: Abstract The internal meanflow with nonuniform distributions of velocity and temperature is a major challenge for acoustic analysis of a muffler in the frequency domain. On the other hand, the three-dimensional time-domain numerical method is well suited for solving the influence of meanflow on the muffler, but it is time-consuming, especially for calculating the transfer matrix that requires two sets of boundary conditions. We proposed a more efficient time-domain method to calculate the scattering matrix (SM) of an actual engine muffler using a numerical model with only one set of boundary conditions. The reciprocity, as a basic property of waves, was for the first time demonstrated in such a complex muffler with hot nonuniform flow exhausted from the engine and used to reduce the procedures for calculating the SM. The reciprocal relationship was not only expressed in the modules of the transmission coefficients in the SM but also corrected in the phases using the time delay between the incident and transmitted waves observed with the time-domain method. At last, the SM was adopted to obtain the performance of the muffler, which was validated with the measurement. The proposed method shall make the time-domain method more efficient for calculating the characterizing matrix of a muffler without or with meanflow.
PubDate: 2022-06-02
DOI: 10.1007/s40857-022-00269-2
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