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In most of the following references, the author's name is followed by the title of the paper or book in boldface, the journal, the volume number in boldface, the issue number in parentheses, the page reference, and lastly, in parentheses, the year. Where reference is made to abstract journals that number their abstracts, the abstract number is given instead of a page reference. Abstracts in Annales des Tèlècommunications are in French and those for Referativnyi Zhurnal, Fizika (three series, E, I, Zh) are in Russian [where, e.g., Ref. Zh. Fiz. 7 E425 (1979) means: July issue, E, abstract no. 425, year 1979.] When possible, the abbreviations for the names of the journals follow those in Bibliographic Guide for Editors & Authors (1974). A number preceded by the letters AD, DE, PB, or N refers to the accession/report number of the Government Reports Announcements & Index. The numbers to the left of the sections and sub-sections in this volume correspond to those that appear in the Classification of Subjects preceding the index in the June 1983 issue of JASA. Compiled from various sources. For many of the journals referred to here, those interested will find their addresses in either the semi-annual Author Index of Physics Abstracts or the annual Physics Briefs: List of Abstracted Periodical and Serial Publications.

Monopole time reversal is an advanced noise source localization technique, but its sidelobe level in localizing sound sources is greatly affected by noise, leading to a decrease in the accuracy of sound source localization under a low signal-to-noise ratio. To address this issue, this paper proposes a time-domain monopole time reversal technique that excludes autocorrelation to reduce the impact of noise on sound source localization results. Numerical simulation and experimental results show that, compared to conventional monopole time reversal techniques, the proposed method can effectively reduce the sidelobes in sound source localization results and achieve accurate sound source localization under −20 dB low signal-to-noise ratio conditions. [ABSTRACT FROM AUTHOR]

Air-conducted (AC) microphones capture the high-quality desired speech and ambient noise, whereas bone-conducted (BC) microphones are immune to ambient noise but only capture band limited speech. This paper proposes a speech enhancement model that leverages the merits of BC and AC speech. The proposed model takes the spectrogram of BC and AC speech as input and fuses them by an attention-based feature fusion module. The backbone network of the proposed model uses the fused signals to estimate mask of the target speech, which is then applied to the noisy AC speech to recover the target speech. The proposed model adopts a lightweight design of densely gated convolutional attention network (DenGCAN) as the backbone network, which contains encoder, bottleneck layers, and decoder. Furthermore, this paper improves an attention gate and integrates it into skip-connections of DenGCAN, which allows the decoder to focus on the key areas of the feature map extracted by the encoder. As the DenGCAN adopts self-attention mechanism, the proposed model has the potential to improve noise reduction performance at the expense of an increased input-output latency. Experimental results demonstrate that the enhanced speech of the proposed model achieves an average 1.870 wideband-PESQ improvement over the noisy AC speech., (© 2024 Acoustical Society of America.)

The template matching method has been widely utilized in the defect detection of wafer surfaces. However, the traditional matching approaches are limited by illumination, noise, and deformation, which cannot meet the requirements of accuracy and robustness. In this paper, a novel multiple targets localization method, named Normalized Cross-correlation Adaptive Variable Step-Size Dynamic Template (NCC-AVSSDT) matching, is proposed to improve the accuracy and efficiency of image localization, which combines the advantages of NCC and AVSSDT. The AVSSDT method is utilized to dynamically adjust the scanning step size based on the NCC matching coefficients. This approach optimizes the scanning process, accelerating convergence toward the optimal matching position. Experimental results verify the accuracy and robustness of the proposed method under different conditions, especially when dealing with rotational variations and variations in noise textures. Therefore, NCC-AVSSDT can be used to perform multiple targets localization of chip image in nearly real-time. Three experiment types were used for comprehensive evaluations, including multiple targets, noise, and rotation angles. Experimental results show that NCC-AVSSDT is much better than the sequential similarity detection algorithm and mean absolute deviation methods in terms of multiple targets (0.667 vs 0.811 s, 0.832 s) and success rate (100% vs 35%, 20%). [ABSTRACT FROM AUTHOR]

This paper presents the results of a listening experiment designed to assess annoyance and perceived loudness (PL) for several unmanned aircraft system (UAS) operations, with the listener simulated in indoor and outdoor positions. This research investigated (i) how participant responses change depending on UAS operation, (ii) which broadband metrics are most suitable for representing annoyance and PL, (iii) differences in noise level required to result in equal participant responses to different operations, and (iv) which sound quality metrics (SQMs) are significant for UAS noise perception. Results indicate annoyance and PL responses were greatest for landing operations with flyovers being the least annoying or loud. LAeq, LASmax, and loudness (N5) were the strongest predictors in representing annoyance. Offset analysis predicted small differences in annoyance responses between flyovers and other operations, but also indicated that flyovers would require an increase to LASmax of 3.3 to 6.3 dB compared to other operations to achieve equal PL. Loudness was the most significant SQM, with minor contributions from impulsivity for annoyance and PL when outside, and tonality for PL when indoors. These findings contribute to the understanding of UAS noise perception for the development of metrics and assessment methods accounting for the characteristics of UAS operations., (© 2024 Acoustical Society of America.)

This paper introduces an improved weighted nuclear norm with a total variation model tailored for removing multiplicative noise. The model incorporates a weight matrix to regularize the residual matrix, effectively leveraging image redundancy to differentiate various statistical properties of the noise. Since there is no guarantee of a unique solution, the model is reformulated as a linear equality constraint problem and decomposed into two subproblems. These are addressed by using the alternating direction method of multipliers and the split Bregman method, respectively. In addition, each alternative update step has a closed-form and convergent solution. After obtaining the denoised image in the log-domain, the recovered image is given by using the exponential function and bias correction. Experimental evaluations demonstrate the efficacy of our algorithms in enhancing image restoration quality. [ABSTRACT FROM AUTHOR]

The two-dimensional distribution method based on the laser spectrum is widely used in the reconstruction of two-dimensional temperature fields or concentration fields. However, the existing methods are all based on small-scale measurements. In large-scale spatial detection of farmland, the detection accuracy cannot reach the expected result due to the long optical path and the noise of various frequencies brought by environmental factors such as vibration, temperature, and other interfering gases. Aiming at the above-mentioned problems, this paper proposes a method to reduce open optical path noise interference in two-dimensional gas detection of farmland to improve detection accuracy. The signal denoising approach combines variational modal decomposition with the SG filtering algorithm to decompose, smooth out, and rebuild the detection signal. In addition, we built a two-dimensional detection system based on an open optical path. Throughout experimental validation, the proposed method outperformed the traditional method by 24% and 19%, respectively, in terms of the fitting degree and fitting effect of the gas absorption curve. [ABSTRACT FROM AUTHOR]

The robust assessment of noise annoyance is of key importance given that it is the most prevalent community response in populations exposed to environmental noise. In 1993, the International Commission on Biological Effects of Noise Community Response to Noise team began formalizing a standardized methodology for assessing noise annoyance which resulted in reporting guidelines and recommendations later published as a Technical Specification (TS) in 2003 by the International Standards Organization (ISO) [(2003). ISO/TS 15666]. This TS, intended to inform the international community on the quantification of the exposure-response relationship between noise exposure and annoyance, has been in circulation for nearly two decades and was updated in 2021 by ISO [(2021). ISO/TS 15666] by an international working group (ISO TC43/SC1/WG62). This paper reviews use of the 2003 TS, identifies common adaptations in use, and summarizes the revisions. Methodological issues arising from the use of the 5-point verbal and the 11-point numeric scale questions and the scoring of "highly annoyed" are discussed. The revisions are designed to encourage further standardization in noise annoyance research. The paper highlights research needs that, if addressed, would strengthen the methodology underlying the assessment of noise annoyance including multidimensional assessments of annoyance. [ABSTRACT FROM AUTHOR]

The application of acoustic liners near/directly over a sound source has gained significant interest for the excess noise reduction achieved with Over-the-Rotor (OTR) liners compared to the conventional liner installations at the intake of an aero-engine. However, the mechanism of noise reduction achieved in the OTR liners is not clearly understood. This paper aims to explain this mechanism by considering a static monopole source placed over a finite liner insert with a zero background mean flow. This has been investigated numerically using COMSOL Multiphysics in a half-space domain and compared with reference analytical solutions for infinite lined walls. One of the key findings of the paper is the underlying physics of the source modification mechanism, which has been found to be the interference between the primary noise source and a secondary noise source forming on the liner surface. It is identified through an optimal impedance study that this back-reaction mechanism is dominant when the source is located for a normalised tip gap, e / λ < 0.25 , where e is the distance between the source and the liner surface and λ is the acoustic wavelength. Within this region, there exists an optimum normalised liner length, L / e providing a maximum insertion loss. [ABSTRACT FROM AUTHOR]

Magnetoresistive (MR) sensors have great application prospects in the field of weak magnetic field detection due to their high sensitivity, small size, and low power consumption. However, 1/f noise greatly limits the low-frequency detectivity of MR sensors. In order to suppress 1/f noise, this paper proposes a two-dimensional synchronous motion modulation (TDSMM) structure based on microelectromechanical systems (MEMS). This structure can effectively reduce 1/f noise by modulating the frequency of the measured magnetic field in the high-frequency band. Theoretical analysis and finite element simulation were conducted on three different modulation models: TSDMM, magnetic flux concentrators motion modulation, and MR components longitudinal motion modulation. The results showed that the modulation efficiency of the TDSMM reached as high as 127%, which is currently the highest value in MR-MEMS sensors. The TDSMM MEMS structure has been successfully manufactured, and the resonant frequency of the transverse resonator is twice that of the longitudinal resonator, enabling extremely high modulation efficiency. The noise spectral density of giant-magnetoresistive components on a silicon-on-insulator substrate was tested, and the noise level in the high-frequency band was three orders of magnitude lower than that in the low-frequency band. These results position MR-MEMS sensors with TDSMM structures as highly competitive candidates in the field of ultra-weak magnetic field detection. [ABSTRACT FROM AUTHOR]

Sea ice and freshwater ice can be different in terms of physical and acoustic characteristics, such as density, salinity, etc. In this paper, under-ice ambient noise in the Mudan river (Jilin Province, Northeast of China) is analyzed using the data recorded by autonomous hydrophones to test if the river ice environment is an effective analog for studying under-ice noise of multi-year ice sheets in the Arctic. The noise spectrum level below 250 Hz and above 1 kHz decreases linearly with the increase in the logarithmic frequency in a quiet environment. The ice cracks are detected and extracted, and Pearson correlation analysis between meteorological information and cracks is carried out. Frequency correlation matrixes are calculated to obtain the correlation between pairs of frequencies and evaluate the frequency correlation of ice crack noise of two hydrophones under different depths, different distances, and different times. Finally, the paper compares the experimental results with Arctic under-ice noise in the literature. Similarities with Arctic under-ice noise are observed in the experiment, including noise spectrum, cracks' peak frequency, and correlations between temperature and crack intensity. This paper believes that the study of under-ice noise in freshwater rivers can be used to simulate multi-year ice regions in the Arctic in terms of thermal-induced cracks and meteorological correlation. And future research is needed to prove this judgment further. [ABSTRACT FROM AUTHOR]

The potential effects of underwater anthropogenic sound and substrate vibration from offshore renewable energy development on the behavior, fitness, and health of aquatic animals is a continuing concern with increased deployments and installation of these devices. Initial focus of related studies concerned offshore wind. However, over the past decade, marine energy devices, such as a tidal turbines and wave energy converters, have begun to emerge as additional, scalable renewable energy sources. Because marine energy converters (MECs) are not as well-known as other anthropogenic sources of potential disturbance, their general function and what is known about the sounds and substrate vibrations that they produce are introduced. While most previous studies focused on MECs and marine mammals, this paper considers the potential of MECs to cause acoustic disturbances affecting nearshore and tidal fishes and invertebrates. In particular, the focus is on particle motion and substrate vibration from MECs because these effects are the most likely to be detected by these animals. Finally, an analysis of major data gaps in understanding the acoustics of MECs and their potential impacts on fishes and aquatic invertebrates and recommendations for research needed over the next several years to improve understanding of these potential impacts are provided., (© 2023 U.S. Government.)

An improved method based on the second order improved central difference method is proposed to improve the third-order magnetic gradient tensor, which is affected by noise and characterized by poor stability. The third-order magnetic gradient tensor at the center point is calculated by using the three-component magnetic field at four points along a single route; this approach effectively improves the stability of the third-order magnetic gradient tensor data. In this paper, the errors of the traditional method and the new method in calculating the third-order magnetic gradient tensor are given by the Taylor series. Based on the traditional third-order magnetic gradient tensor system, a new third-order magnetic gradient tensor system and the corresponding measurement method are presented. Through simulations, in the case of noise, it is verified that the proposed method exhibits better stability by comparing the components of the third-order magnetic gradient tensor with the positioning results. In experiments, the root-mean-square error is used to compare the positioning results before and after noise addition. The traditional method changes the root-mean-square error of the positioning results from (1.3626, 3.6573, 0.5766 m) to (3.3661, 9.5966, 1.9465 m), and the root-mean-square error obtained with the new method displays no obvious change. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicle (UAV) technologies are rapidly advancing due to the unlimited number of applications from parcel delivery to people transportation. As the UAV market expands, community noise impact will become a significant problem for public acceptance. Compact drone architectures based on contra-rotating propellers bring significant benefits in terms of aerodynamic performance and redundancy to ensure vehicle control in case of component failure. However, contra-rotating propellers are severely noisy if not designed appropriately. In the framework of a perception-influenced design approach, this paper investigates the optimal rotor spacing distance configuration to minimise noise annoyance. On the basis of a series of psychoacoustic metrics (i.e., loudness, fluctuation strength, roughness, sharpness, and tonality) and psychoacoustic annoyance (PA) models, the optimal rotor axial separation distance (expressed as a function of propeller blade diameter) is at a range from 0.2 to 0.4. This paper also discusses the performance of currently available psychoacoustic models to predict propeller noise annoyance and defines further work to develop a PA model optimised for rotating systems. [ABSTRACT FROM AUTHOR]

The tunnel magnetoresistance (TMR) sensor has the advantages of high sensitivity, easy miniaturization, and low power consumption, and it has the great potential to become a high-performance magnetic field measurement sensor. As the TMR magnetic sensor has complex noise characteristics, it is of great significance to explore the noise characteristics of TMR magnetic sensor for guiding its application. In this paper, the noise characteristics of the TMR magnetic sensor under different excitations are studied. It is found that the noise of TMR magnetic sensor under AC excitation is separated: some of the noise is dependent on the excitation and is moved to the excitation frequency synchronously with the output signal. The remaining part of the noise is independent of the excitation and remains in the low frequency band. Through the quantitative analysis of noise data, we find that the noise related to excitation accounts for about 70% of the total noise, while the noise unrelated to excitation accounts for about 30%. The results show that under AC excitation, 70% of the noise is synchronously modulated and 30% of the noise is separated from the signal, which provides an important guidance for the application of TMR magnetic sensor. [ABSTRACT FROM AUTHOR]

During NASA X-59 quiet supersonic aircraft community response tests, low-boom recordings will contain contaminating noise from instrumentation and ambient acoustical sources. This noise can inflate sonic boom perception metrics by several decibels. This paper discusses the development and comparison of robust lowpass filtering techniques for removing contaminating noise effects from low-boom recordings. The two filters are a time-domain Butterworth-magnitude filter and a frequency-domain Brick Wall filter. Both filters successfully reduce noise contamination in metric calculations for simulated data with real-world contaminating noise and demonstrate comparable performance to a modified ISO 11204 correction. The Brick Wall filter's success indicates that further attempts to match boom spectrum high-frequency roll-off beyond the contaminating noise floor are unnecessary and have marginal improvements on final metric calculations. Additionally, the Butterworth filter removes statistical correlation between ambient and boom levels for a real-world flight campaign, adding evidence that these techniques also work on other boom shapes. Overall, both filters can produce accurate metric calculations with only a few hundred hertz of positive signal-to-noise ratio. This work describes methods for accurate metric calculations in the presence of moderate noise contamination that should benefit X-59 and future low-boom supersonic aircraft testing. [ABSTRACT FROM AUTHOR]

Frequency hopping (FH) signals have been widely used to improve performance against frequency selective fading phenomenon of underwater channels. However, the channel is slowly varying in regard to changes in weather conditions, and thus the conventional FH detection transmitting signals with fixed frequency cannot guarantee good detection performance in the dynamic underwater environment. To overcome the performance degradation in slowly-varying fading dispersive channels, this paper proposes an adaptive frequency-hopping (AFH) target detection method. Compared with conventional FH detection methods, the AFH can adaptively select the optimal detection frequency based on premeasured background noise and channel frequency response measured from previous experiments. Numerical simulations and lake trials are conducted to verify the effectiveness of the AFH. The simulation results show that the AFH has better detection performance than the conventional FH. The lake trial results have also verified the validity and feasibility of AFH. Importantly, AFH also achieves a better output signal-to-noise ratio under actual noise interference. [ABSTRACT FROM AUTHOR]

This paper aims to propose a noise profiling method that can be performed in near real time based on machine learning (ML). To address challenges related to noise profiling effectively, we start with a critical review of the literature background. Then, we outline the experiment performed consisting of two parts. The first part concerns the noise recognition model built upon several baseline classifiers and noise signal features derived from the Aurora noise dataset. This is to select the best-performing classifier in the context of noise profiling. Therefore, a comparison of all classifier outcomes is shown based on effectiveness metrics. Also, confusion matrices prepared for all tested models are presented. The second part of the experiment consists of selecting the algorithm that scored the best, i.e., Naive Bayes, resulting in an accuracy of 96.76%, and using it in a noise-type recognition model to demonstrate that it can perform in a stable way. Classification results are derived from the real-life recordings performed in momentary and averaging modes. The key contribution is discussed regarding speech intelligibility improvements in the presence of noise, where identifying the type of noise is crucial. Finally, conclusions deliver the overall findings and future work directions.

When making voice interactions with hands-free speech communication devices, direction-of-arrival estimation is an essential step. To address the detrimental influence of unavoidable background noise and interference speech on direction-of-arrival estimation, this paper introduces a stacked self-attention network system, a supervised deep learning method that enables utterance level estimation without requirement for any pre-processing such as voice activity detection. Specifically, alternately stacked time- and frequency-dependent self-attention blocks are designed to process information in terms of time and frequency, respectively. The former blocks focus on the importance of each time frame of the received audio mixture and perform temporal selection to reduce the influence of non-speech and interference frames, while the latter blocks are utilized to derive inner-correlation among different frequencies. Additionally, the non-causal convolution and self-attention networks are replaced by causal ones, enabling real-time direction-of-arrival estimation with a latency of only 6.25 ms. Experiments with simulated and measured room impulse responses, as well as real recordings, verify the advantages of the proposed method over the state-of-the-art baselines.

Air cavities in the tyre tread and the gap formed between tyre and pavement are excited during vehicle movement on a pavement. The former results in pipe resonance, and the latter results in horn resonance. These effects will be varying with speed of the vehicle and also because of conditions of tyre, pavement and, tyre-pavement interaction (TPI). The objective of this paper is to study the dynamic characteristics of air cavity resonances from the signals of the tyre-pavement interaction noise, which was collected by a pair of microphones, when a two wheeler is driven on a pavement at different speeds. The dynamic characteristics of the resonances are analysed using single frequency filtering (SFF) analysis of signals. The method gives spectral information at every sampling instant. The effects of impacts of the tyre treads, pavement characteristics, and TPI on the resulting cavity resonances are examined at four different vehicle speeds and for two different types of pavements. The analysis shows that the SFF spectra bring out the distinct characteristics of the pavements on the formation of air cavities and excitation of the resonances of these cavities. This analysis may help in determining the condition of the tyre and pavement. [ABSTRACT FROM AUTHOR]

This paper presents a noise propagation approach based on the Gaussian beam tracing (GBT) method that accounts for multiple reflections over three-dimensional terrain topology and atmospheric refraction due to horizontal and vertical variability in wind velocity. A semi-empirical formulation is derived to reduce truncation error in the beam summation for receivers on the terrain surfaces. The reliability of the present GBT approach is assessed with an acoustic solver based on the finite element method (FEM) solutions of the convected wave equation. The predicted wavefields with the two methods are compared for different source-receiver geometries, urban settings, and wind conditions. When the beam summation is performed without the empirical formulation, the maximum difference is more than 40 dB; it drops below 8 dB with the empirical formulation. In the presence of wind, the direct and reflected waves can have different ray paths than those in a quiescent atmosphere, which results in less apparent diffraction patterns. A 17-fold reduction in computation time is achieved compared to the FEM solver. The results suggest that the present GBT acoustic propagation model can be applied to high-frequency noise propagation in urban environments with acceptable accuracy and better computational efficiency than full-wave solutions. [ABSTRACT FROM AUTHOR]

Long-range passive source localization is possible in the deep ocean using phase-only matched autoproduct processing (POMAP) [Geroski and Dowling (2021). J. Acoust. Soc. Am. 150, 171–182], an algorithm based on matched field processing that is more robust to environmental mismatch. This paper extends these prior POMAP results by analyzing the localization performance of this algorithm in the presence of environmental noise. The noise rejection performance of POMAP is assessed using both simulated and measured signal data, with noise data based on environmental noise measurements. Herein, signal and noise measurements are from the nominally one-year-long PhilSea10 ocean acoustic propagation experiment. All signals were recorded from a single moored source, placed near the ocean sound channel 129.4 km away from a nearly water-column-spanning distributed vertical line array. The source transmitted linear frequency modulated chirps with nominal bandwidth from 200 to 300 Hz. The noise measurements used in this study were collected in the months after this source stopped transmitting, and synthetic samples of noise are calculated based on the characteristics of this measured noise. The effect that noise rejection algorithms have on the source localization performance of POMAP is also evaluated, but only 1 dB of performance improvement is achieved using these. [ABSTRACT FROM AUTHOR]

Systematic advances in the resolution and analytical interpretation of acoustic emission (AE) spectroscopy have, over the last decade, allowed for extensions into novel fields. The same dynamic failure patterns, which have been identified in earthquakes, magnetism, and switching of ferroelastic and ferroelectric materials, are shown, in this paper, to be equally important in medicine, and minerals, in the geological context, to give just two examples. In the first application, we show that biological samples, i.e., kidney stones, can be analyzed with acoustic emission and related to the progression of mechanical avalanches. Discrepancies between strong and weak AE signals are shown to have separate avalanche exponents for a urate kidney stone, with evidence of slight multi-branching. It is proposed that investigations of this nature can be adopted to the field of medicine, and in the case of kidney stones, can provide a blueprint for selecting ideal combinations of energy and frequency to instigate their destruction. In a second example, porous geological material failure is shown to proceed equally in avalanches, and precursors to catastrophic failure can be detected via AE. Warning signs of impeding macroscopic collapse, e.g., in mining activities, show systematic evolution of energy exponents. Ultimately, this behavior is a result of geological processes, man-made bio-mineralization, or the burning of carbon inclusions, creating pores and holes, causing cracks, and accelerating their interactions. [ABSTRACT FROM AUTHOR]

The International Standards Organization (ISO) published Technical Specification (TS) 15666 in 2003 to facilitate the comparison of results from surveys on noise annoyance. This document recommends including two standardized questions with two standardized response scales in all surveys of long-term noise annoyance. A recently revised version of the TS proposes a weighting procedure for the response data to achieve a better similarity between the results from the two questions. This paper analyses the results from 43 surveys conducted according to the ISO/TS 15666 recommendations. It is shown that the average difference in the response to the two annoyance questions is equivalent to a 6 dB shift in the exposure level. The proposed weighting of the verbal response whereby response category 5 (extremely) is counted in full, and category 4 (very) is weighted by a factor 0.4 creates a greater similarity between the two responses. It is important to use a definition of prevalence of high annoyance which matches the one used for the development of the relevant noise regulations.

The aerodynamic noise of pipelines is an important part of the noise of a ship's system. This paper conducted numerical investigations on the flow and acoustic characteristics of the marine gas turbine exhaust system. The near-field and far-field acoustic characteristics of the internal flow noise of the exhaust system are calculated by employing the Möhring's sound analogy method. In addition, the far-field acoustic characteristics of the external jet flow noise of the exhaust system are calculated by employing the stochastic noise generation and radiation (SNGR) method. Two kinds of protrusions are added to the main nozzle outlet to achieve noise reduction. The internal sound field of the marine exhaust system is dominated by low frequency sound sources, which are more obvious as the exhaust mass flow rate decreases. As for the external sound field of the marine exhaust system, the peak frequency of the far-field noise spectrum decreases with the decrease in the exhaust mass flow rate. The eight periodic protrusions perform better in reducing the internal aerodynamic noise of the exhaust system, while the five aperiodic protrusions perform better in reducing the external jet noise of the exhaust system. [ABSTRACT FROM AUTHOR]

In community noise studies, there is often a desire to understand how the annoyance response to multiple noise events aggregates over a long period of time. Many cumulative response metrics, such as day-night level (DNL), are based on the idea that humans respond, on average, to the sum of frequency-weighted acoustic energy over time. This paper introduces a generalization of DNL that includes a parameter, b , that ranges between zero and one. When b equals zero, the metric returns the maximum level of the events. When b equals 0.5, the metric reproduces the equal-energy-based output of DNL. When b = 0, 0.5, and 1, the metric returns a value that more harshly penalizes the number of events. In this way, these common possible hypotheses are organized onto a single scale, one that may be used to craft effective noise mitigation techniques or implement regulations. The analysis is demonstrated in two ways: first, on synthetic datasets to show the utility and consistency of the metric, and second, on limited quiet-supersonic response data gathered during the Quiet Supersonic Flights 2018 community study. [ABSTRACT FROM AUTHOR]

Simultaneous perturbation stochastic approximation (SPSA) algorithm, an algorithm without secondary path modeling, has been applied to active noise control by some researchers. Some extended versions of this algorithm have been also developed to improve its performance. However, these existing algorithms are mostly dedicated to controlling the periodic noise instead of the broadband noise. In particular, background noise is not taken into account when SPSA algorithms are applied to control broadband noise. In this paper, an algorithm combining the cost function with the SPSA algorithm to control broadband noise has been proposed. The suggested cost function is an inner product of the estimated cross-correlation function between a reference vector and the error signal. The elements of the reference vector are composed of the reference signals at different times. Moreover, the algorithm analysis is performed and the numerical simulations are carried out to demonstrate the validity of the proposed algorithm. The results illustrate that the proposed algorithm can effectively reduce broadband noise when interference noise exists in the control system. Furthermore, the proposed algorithm has better convergence performance than other SPSA algorithms. [ABSTRACT FROM AUTHOR]

This paper proposes an experimental setup for measuring the sound radiation of a quadrotor drone using a hemispherical microphone array. The measured sound field is decomposed into spherical harmonics, which enables the evaluation of the radiation pattern to non-probed positions. Additionally, the measurement setup allows the assessment of noise emission and psychoacoustic metrics at a wide range of angles. The obtained directivity patterns using a third-order spherical harmonic decomposition (SHD) are shown to exhibit low distortion with respect to the original measurements, therefore, validating the SHD as an adequate representation strategy. Furthermore, the noise emissions are evaluated, and the highest noise emission is observed in the 90 ° azimuth direction. The exterior spherical acoustic holography description is employed to evaluate psychoacoustic metrics at arbitrary far-field positions and validated on a reference microphone. The estimated psychoacoustic metrics are closely related to the target metrics, which allows for sound quality analysis at any point external to the drone. [ABSTRACT FROM AUTHOR]

The Detection of Envelope Modulation on Noise (DEMON) is an algorithm that is commonly applied to hydrophone data for the detection and classification of underwater noise produced by a ship. This algorithm utilizes modulation analysis to determine the frequencies that modulate the broadband cavitation noise produced by marine vessel propellers. In this paper, a DEMON demodulator for acoustic vector sensors (AVSs) that are directional hydrophones capable of acquiring both the acoustic pressure and the components of the particle velocity vector is defined. The proposed method is able to extract multiple modulating signals and measure their direction of arrival. The proposed receiver was validated with real data collected at sea with a moving buoyancy glider hosting an AVS. [ABSTRACT FROM AUTHOR]

The aviation sector is rapidly evolving with more electric propulsion systems and a variety of new technologies of vertical take-off and landing manned and unmanned aerial vehicles. Community noise impact is one of the main barriers for the wider adoption of these new vehicles. Within the framework of a perception-driven engineering approach, this paper investigates the relationship between sound quality and first order physical parameters in rotor systems to aid design. Three case studies are considered: (i) contra-rotating versus single rotor systems, (ii) varying blade diameter and thrust in both contra-rotating and single rotor systems, and (iii) varying rotor-rotor axial spacing in contra-rotating systems. The outcomes of a listening experiment, where participants assessed a series of sound stimuli with varying design parameters, allow a better understanding of the annoyance induced by rotor noise. Further to this, a psychoacoustic annoyance model optimised for rotor noise has been formulated. The model includes a novel psychoacoustic function to account for the perceptual effect of impulsiveness. The significance of the proposed model lies in the quantification of the effects of psychoacoustic factors, such as loudness as the dominant factor, and also tonality, high frequency content, temporal fluctuations, and impulsiveness on rotor noise annoyance.

Aerofoils operating in a turbulent flow are an efficient source of noise radiation by scattering vorticity into sound at the leading edge (LE). Much work has now been undertaken demonstrating the effectiveness of serrations, or undulations, introduced onto the LE can substantially reduce broadband LE interaction noise. However, all of this work is focused on sinusoidal LE serration profiles. In this paper, an alternative profile is proposed that is capable of providing significantly greater noise reductions than the maximum noise reductions that can be achieved by single-wavelength serrations of the same peak-to-root amplitude. In its most general realization, the LE serration profiles simply comprise of a sawtooth or single wavelength serration for which every root has a single narrow slit. This simple geometry, upon interaction with a turbulent flow, produces compact source regions at either end of the slit, which then destructively interfere, leading to considerably less efficient noise radiation than conventional single-wavelength geometries. The paper will demonstrate experimentally that even slits by themselves can provide greater levels of noise reduction than conventional profiles of the same peak-to-root amplitude. [ABSTRACT FROM AUTHOR]

A covariance fitting algorithm for the estimation of direction-of-arrivals of multiple incident signals is addressed in this paper. The scheme takes advantage of the fact that the incident signals are spatially sparse. A previous study has presented the regularization parameters of the covariance fitting for a very large number of snapshots. In this paper, a strategy on how to determine the regularization constant of the covariance fitting for a general number of snapshots is presented. The strategy essentially exploits the norm of the noise covariance matrix. The proposed algorithm has been validated via numerical simulations. [ABSTRACT FROM AUTHOR]

The focus of this paper is the estimation of the dynamic transfer function between two outputs of a linear system subjected to an uncontrolled and generally unknown excitation, and accounting for possible uncorrelated noise present at both outputs. Several applications of this case exist in the passive identification of dynamic systems including the health monitoring and/or non-destructive evaluation of structures subjected to natural “ambient” excitations. It is well known that noise-robust transfer function estimation of a single-input-single-output system can be achieved by a normalized cross-power spectrum operation. This paper shows that, for the subject case of a dual-output system, particular caution must be placed in the choice of the normalization factor to apply to the cross-power spectrum of the two outputs. In particular, an “inter-segment” averaging method is proposed for the normalization factor in combination with the classical “intra-segment” averaging of the cross-power spectrum in order to estimate the transfer function between the two outputs without the influence of the excitation spectrum and of the uncorrelated noise at the two receivers. Validating results are presented for synthetic signals and for experimental signals from an application to high-speed ultrasonic rail inspection exploiting the train wheels as the “ambient” excitation. [ABSTRACT FROM AUTHOR]

Spectrogram analysis is a vital skill for learning speech acoustics. Spectrograms are necessary for visualizing cause-effect relationships between speech articulator movements and the resulting sound produced. However, many interpretation techniques needed to read spectrograms are counterintuitive to engineering students who have been taught to use more rigid mathematical formulas. As a result, spectrogram reading is often challenging for these students who do not have prior background in acoustic phonetics. In this paper, a structured, inclusive framework for teaching spectrogram reading to students of engineering backgrounds is presented. Findings from the implementation of these teaching methods in undergraduate and graduate engineering courses at University of California, Los Angeles are also unveiled. [ABSTRACT FROM AUTHOR]

This paper analyzes the impact of second wave of COVID-19 lockdown on environmental noise levels of 25 sites in Delhi city and compares the noise scenario during pre-lockdown, lockdown, and post-lockdown periods. The study utilized the noise monitoring data acquired from 25 real-time ambient noise monitoring stations, installed by the Delhi Pollution Control Committee, Delhi, at various sites throughout Delhi city. A significant reduction of up to 10 and 3 dB(A) in day and night equivalent noise levels, respectively, had been observed during the lockdown period as compared to the pre-lockdown and post-lockdown periods. The study also revealed that only nine sites, including four industrial and five commercial zone sites, complied with the ambient noise standards during lockdown period, and no silence or residential zone sites complied with the ambient noise standards even during the lockdown period. A roadmap for environmental noise management and control is suggested. The study also reports the community's perception toward the change in acoustic environment of Delhi city during the lockdown period by conducting an environmental noise perception survey. The present study should be helpful in devising noise control action plans and policy interventions for environmental noise management and control in the metropolitan city Delhi, India. [ABSTRACT FROM AUTHOR]

Sound generated by pile installation using a down-the-hole (DTH) hammer is not well documented and differs in character from sound generated by conventional impact and vibratory pile driving. This paper describes underwater acoustic characteristics from DTH pile drilling during the installation of 0.84-m shafts within 1.22-m steel piles in Ketchikan, Alaska. The median single-strike sound exposure levels were 138 and 142 dB re 1 μPa 2 s at 10 m for each of the two piles, with cumulative sound exposure levels of 185 and 193 dB re 1 μPa 2 s at 10 m, respectively. The sound levels measured at Ketchikan were significantly lower than previous studies, and the sound was determined to be non-impulsive in this study as compared to impulsive in previous studies. These differences likely result from the DTH hammer not making direct contact with the pile, as had been the case in previous studies. Therefore, we suggest using the term DTH pile drilling to distinguish from DTH pile driving when the hammer strikes the pile. Further research is needed to investigate DTH piling techniques and associated sound-generating mechanisms and to differentiate the various types of sound emitted, which has important implications for the underwater sound regulatory community.

Acoustic trauma (AT) is permanent hearing loss after a single noise exposure. A few human cases resulting from continuous, i.e., nonimpulsive noise, have been reported as reviewed by Ward [(1991). "Hearing loss from noise and music," presented at Audio Engineering Society, New York, October 4–8]. This paper updates that review by examining 11 cases in nine reports, from 1950 to 2006, with the intention of determining minimum exposures that may cause AT, including the potential risk of exposure to noise from magnetic resonance imaging machines. Diffuse-field related levels above 120 dBA for 10 s or more, or above 130 dBA for 2–3 s (values well above OSHA's unprotected exposure limits), can lead to AT. These cases appear to represent a susceptible fraction of the population, because much more intense exposures (e.g., 130 dBA for 32 min) have been tolerated by groups of volunteers who suffered only temporary threshold shifts. AT from continuous noise is unlikely to occur in OSHA-compliant hearing conservation programs, and probably rare enough in the general civilian population that clinical trials of drugs aimed at treating it are unlikely to be practical. AT from impulse noise, such as gunfire, which is specifically not the topic of the current work, is more amenable to clinical trials, especially in military settings. [ABSTRACT FROM AUTHOR]

Detecting the presence or absence of a known signal is an important aspect of underwater acoustic (UWA) communications as it is a vital first step to process the received data. The influence of impulsive noise and multipath propagation on detection are both considered in this paper. Many robust detectors have been designed to cope with impulsive noise, but they tend to ignore the impact of multipath propagation, which may decrease the detection probability. To emphasize the role of multipath channel, we propose two-stage detection methods. In the first stage, the channel is estimated based on robust orthogonal matching pursuit, while in the second stage, detectors that use the channel estimation from the first stage, namely augmented log-likelihood ratio detector and augmented pseudo-correlation detector, are developed. The former detector is parametric and the latter one is non-parametric. The improved performance is demonstrated in simulated multipath channel and actual UWA channel with both simulated noise and recorded snapping shrimp noise, indicating that the proposed detectors are resistant to impulsive noise. It is also shown that the use of multipath information helps to improve the detection performance. [ABSTRACT FROM AUTHOR]

The atomic force microscope (AFM) can measure nanoscale morphology and mechanical properties and has a wide range of applications. The traditional method for measuring the mechanical properties of a sample does so for the longitudinal and transverse properties separately, ignoring the coupling between them. In this paper, a data processing and multidimensional mechanical information extraction algorithm for the composite mode of peak force tapping and torsional resonance is proposed. On the basis of a tip–sample interaction model for the AFM, longitudinal peak force data are used to decouple amplitude and phase data of transverse torsional resonance, accurately identify the tip–sample longitudinal contact force in each peak force cycle, and synchronously obtain the corresponding characteristic images of the transverse amplitude and phase. Experimental results show that the measured longitudinal mechanical characteristics are consistent with the transverse amplitude and phase characteristics, which verifies the effectiveness of the method. Thus, a new method is provided for the measurement of multidimensional mechanical characteristics using the AFM. HIGHLIGHTS: • Based on a composite method of peak force tapping and torsional resonance, a multidimensional mechanical signal measurement system for an atomic force microscope (AFM) is constructed that overcomes the inability of the peak force tapping mode to measure the transverse mechanical properties of a sample and the inability of the traditional torsional resonance mode to realize closed-loop feedback control of stable morphology. It can thus obtain both longitudinal and transverse mechanical information of a sample simultaneously. • Based on a model of the interaction between the AFM tip and a sample, longitudinal peak force data is used to synchronize and decouple transverse torsional resonance amplitude and phase data, enabling accurate identification of the longitudinal contact force between tip and sample in each peak force cycle, as well as synchronous acquisition of the corresponding characteristic images of transverse amplitude and phase. • The improved contact point registration algorithm accurately identifies the signal boundary for each peak force cycle, providing a better way of dealing with background noise and obtaining more accurate image data. [ABSTRACT FROM AUTHOR]

The Gaussian beam tracing method has advantages in computing long-distance noise propagation in outdoor environments due to its high efficiency. Usually, repeated computations are required if the target sound wave is broadband or contains multiple frequencies because the method was developed in the frequency domain. This paper presents an efficient computation of broadband noise propagation using Gaussian beam tracing. The approach is based on the fact that the ray behaviors and source properties can be decoupled at high frequencies, where the wave equation is asymptotically solved. Consequently, only a single computation is needed to determine the frequency-independent ray properties, including ray-centered coordinates and beam dynamics. Then sound waves at different frequencies can be simultaneously introduced in a single computation. By separating the processes of determining the ray properties and incorporating the broadband noise source in the numerical implementation, the computational cost can be largely saved. In this work, several benchmark problems are studied, showing that the efficiency could be increased in comparison to the multiple individual computations. A computation acceleration up to 35-fold could be achieved when 200 frequency components are applied. The method is also applied to study the impact of broadband noise due to multiple drone propellers in urban environments. Applications to stochastic broadband problems are also discussed. [ABSTRACT FROM AUTHOR]

The use of earplugs is commonly associated with an increased perception of the bone-conducted part of one's own physiological noise. This phenomenon is referred to as occlusion effect and is most prominent at low frequencies. Several factors influence the occlusion effect, such as the ear anatomy; the bone-conducted stimulation; and the type of occlusion device and its fit, insertion depth, and material properties. The latter factor is of great interest to potentially reduce the occlusion effect of passive earplugs. This paper investigates the mechanism(s) of contribution of earplugs to the objective occlusion effect. A two-dimensional axi-symmetric finite element model of the outer ear is used and investigated in an electro-acoustic framework. Simulation results are shown to compare reasonably well with measurement data, which qualifies the model to study the influence of earplugs on the occlusion effect. Two mechanisms are highlighted: (i) a Poisson effect induced by the normal component of the earcanal wall vibration and (ii) a longitudinal motion caused by the tangential component of the earcanal wall vibration. By varying the geometry of the surrounding tissues, the spatial distribution of the earcanal wall vibration is shown to influence the contribution of the earplug to the occlusion effect.

Carr, Davies, Loubeau, Rathsam, and Klos [J. Acoust. Soc. Am. 148, 414-429 (2020)] found that indoor annoyance caused by sonic booms may be predicted from the A-weighted sound exposure level and the heaviness of the booms. Moreover, they suggest that, irrespective of the outdoor-to-indoor sound reduction, indoor annoyance may be predicted from outdoor sound levels. The present paper shows that their data to some extent also support a model in which the contribution of heaviness is level-dependent and that data reported in the literature point out that it is unlikely that indoor annoyance is independent of the degree of façade attenuation.

Dose-response curves lie at the heart of most global community noise laws/policies. Yet, there is no standard on how to choose the noise dose bins that underlie the curves which describe the relationship between noise and annoyance. This paper strives to understand whether the binning process affects the modeled relationship by examining common binning and curve-fitting procedures. It was found that the subjective choice of bin-width can considerably affect the resulting dose-response curves. The implications of these findings are discussed and recommendations are given to ameliorate the situation so that future studies and policies can avoid these potential pitfalls. [ABSTRACT FROM AUTHOR]

Inside open-plan offices, background noise affects the workers' comfort, influencing their productivity. Recent approaches identify three main source categories: mechanical sources (air conditioning equipment, office devices, etc.), outdoor traffic noise, and human sources (speech). Whereas the first two groups are taken into account by technical specifications, human noise is still often neglected. The present paper proposes two procedures, based on machine-learning techniques, to identify the human and mechanical noise sources during working hours. Two unsupervised clustering methods, specifically the Gaussian mixture model and K-means clustering, were used to separate the recorded sound pressure levels that were recorded while finding the candidate models. Thus, the clustering validation was used to find the number of sound sources within the office and, then, statistical and metrical features were used to label the sources. The results were compared with the common parameters used in noise monitoring in offices, i.e., the equivalent continuous and 90th percentile levels. The spectra obtained by the two algorithms match with the expected shapes of human speech and mechanical noise tendencies. The outcomes validate the robustness and reliability of these procedures.

In this paper, the auditory model developed by Dau, Kollmeier, and Kohlrausch [(1997). J. Acoust. Soc. Am. 102, 2892-2905] was used to simulate the perceptual similarity between complex sounds. As complex sounds, a set of piano recordings was used, whose perceptual similarity has recently been measured by Osses, Kohlrausch, and Chaigne [(2019). J. Acoust. Soc. Am. 146, 1024-1035] using a three-alternative forced-choice discrimination task in noise. To simulate this discrimination task, the auditory model required a new back-end stage, the central processor, which is preceded by several processing stages that are to a greater or lesser extent inspired by physiological aspects of the normal-hearing system. Therefore, a comprehensive review of the model parameters as used in the literature is given, indicating the fixed set of parameter values that is used in all simulations. Due to the perceptual relevance of the piano note onsets, this review includes an in-depth description of the auditory adaptation stage, the adaptation loops. A moderate to high correlation was found between the simulation results and existing experimental data.