bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep learning for large scale conservation bioacoustics—A demonstration on the Malabar whistling thrush and the dhole
Authors: Suresh Namitha , Thomas Benjamin , Wang Sha , Madhusudhana Shyam , Ramesh Vijay , Klinck Holger
Published: November 2023

Over the past several years, deep learning-based algorithms have become the go-to solution in conservation bioacoustics for detecting and classifying animal calls in soundscape recordings. While these algorithms often perform very well, they frequently require specialized computer setups and expertise for training and running, thereby hindering the scalability of conservation bioacoustics solutions. Here we evaluate a new framework to overcome this challenge. We train a ResNet model (ResNet50V2 pre-trained with the ImageNet dataset) using the open-source Python package Koogu (https://github.com/shyamblast/Koogu). We focus on two species of interest: the Malabar whistling thrush (Myophonus horsfieldii), a resident bird of Peninsular India, and the dhole (Cuon alpinus), an endangered canid species native to Asia. Preliminary results for the whistling thrush showed that the model achieved a precision of 0.95 and recall of 0.71 on the test data for a detection threshold of 0.7. The work on the dholes is still ongoing. The trained models are then incorporated into the Raven Pro 1.6.5 sound analysis software (https://ravensoundsoftware.com/), equipped with a Deep Learning Detector functionality, which allows Deep Learning models to be run on acoustic data. The models integrated into the software are made publicly available to other researchers and practitioners enabling them to run the models over their datasets as well as integrate their own custom models into Raven Pro.
Neural encoding of Cantonese and Vietnamese tones
Authors: Loc Sam Vinh , Wong Patrick C. , Vuong Loan , Son Huynh Van , Nguyen Thi Hong Dung , Novitskiy Nikolay
Published: November 2023

The present pilot study investigates the neural encoding of lexical tones in Cantonese and Vietnamese. Better encoding of tones was found in native than non-native tone language speakers in previous research, with fewer studies examining language-specific effects. An identical equipment setup was used to measure neural responses to three lexical tones in Hong Kong (HK) (by Cantonese speakers) and Ho Chi Minh City (by Vietnamese speakers). The three tones were the high rising (35), dipping (214), and low falling (21) tones, of which the 21 and 214 tones were unique to Cantonese and Vietnamese respectively. If better tone encoding is language-specific, Vietnamese and Cantonese adult speakers are expected to show enhanced encoding of these tones. Across the majority of temporal and spectral measures, we did not find significant group differences across tonal categories, suggesting that enhancement of neural encoding found in native speakers was likely to be language general. If confirmed with a larger sample size, these findings may suggest that clinical tools utilizing speech stimuli for the assessment of spoken language processing and its related functions may not necessarily require customization for a specific language. [Work supported by ITF in HK.]
Effect of energetic and informational masking on speech reception performance in middle-aged adults
Authors: Yuasa Mai , Otsuka Sho , Nakagawa Seiji
Published: November 2023

Speech reception in the presence of competing sounds declines in middle age. Experiments on young normal-hearing listeners have revealed that speech reception performance in the presence of competing sounds is determined by the cumulative effects of two different types of masking: energetic masking and information masking. Here we examined how energetic and informational masking degrades speech reception in middle-aged adults. Fifteen young (seven males, eight females, 20–26 years) and seventeen middle-aged (four males, thirteen females, 47–57 years) listeners with normal hearing participated in the experiment. Speech reception in the presence of competing sounds was assessed by the Coordinated Response Measure. Participants were required to listen to a target phrase spoken by a female in the presence of noise or a single interfering phrase spoken by the same talker, same-sex talker, or different-sex talker. Speech reception performance was lower in middle-aged adults than young adults, regardless of the type of disturbing sounds. The performance differences between the same-talker and different-sex talker conditions, which reflects the effects of informational masking, was larger in middle-aged adults. These results suggest that both energetic and informational masking contributes to the degradation of speech reception in middle-aged adults.
Estimates of geoacoustic parameters and source range using airgun sound in the East Siberian Sea, Arctic Ocean
Authors: Lee Dae Hyeok , Choi Jee Woong , Han Dong-Gyun , Son Wuju , La Hyoung Sul , Yang Eun Jin
Published: November 2023

In a shallow-water waveguide, low-frequency sound propagating over several kilometers has dispersive properties and thus the dispersion curves can be used for the inversion of geoacoustic parameters. In September 2019, seismic survey was conducted by the icebreaking research vessel Araon, operated by Korea Polar Research Institute. A single hydrophone was moored at East Siberian Shelf, a nearly range-independent shallow water (<70 m), to receive seismic airgun sounds generated from the R/V Araon. It was observed that the arrivals corresponding to the first two modes were clearly dispersed in the spectrogram of the received signal. In order to use these dispersion curves for the geoacoustic inversion, the dispersion curves corresponding to the first two modes were extracted using the warping transform combined with the wavelet synchrosqueezing transform. Geoacoustic parameters including sound speed and density in the sediment and the distance between the source and receiver were then estimated by comparing the extracted dispersion curves to the model replicas predicted by the KRAKEN normal-mode acoustic propagation model. Finally, the inversion results and their error analysis will be discussed in this talk. [This research was a part of the project titled ‘Korea-Arctic Ocean Warming and Response of Ecosystem (K-AWARE, KOPRI, 1525011760)’, funded by the Ministry of Oceans and Fisheries, Korea and supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (2020R1A2C2007772).]
Geometric solutions for focusing retroreflectors
Authors: Holmes Jonothan , Lu Shuai , Cabrera Densil
Published: November 2023

Although focusing might normally be an architectural acoustician’s nightmare, combining it with retroreflection is potentially beneficial. Focusing acoustic retroreflectors concentrate early reflected sound onto arbitrarily located sources. Dihedral and trihedral retroreflectors can be made to focus by curving one or more of their faces in either one or two dimensions. The relationship between curvature and focal distance is developed empirically using analytic ray tracing and finite-difference time-domain methods. Dihedra can be made more compact by segmenting the cross-sectional curvature similar to the Fresnel lens. Complexities of fabricating doubly curved surfaces can be overcome by approximating with several flat surfaces and physical examples are constructed from bending sheet-steel. Simplified designs are shown to achieve similar performance to ideally curved focusing retroreflectors. For context, performance is compared to coherent and incoherent summation of a perfectly reflecting spherical surface of equivalent solid angle, as well as an equivalent flat surface. Results show increased speech-weighted retroreflected energy level and concentration of sound in the region surrounding the collocated source-receiver over the upper range of typical human speech (1 kHz–8 kHz octave bands) when compared to non-focusing retroreflectors, and substantial increases in reflected energy level compared to a specular reflection at normal incidence.
Automatic click detector for sperm and beaked whale distribution monitoring
Authors: Sidenko Evgenii , Parnum Iain M. , Gavrilov Alexander , Erbe Christine
Published: November 2023

Passive acoustic monitoring (PAM) is an effective method for monitoring marine fauna. Automatic detection, identification, and quantification of echolocation clicks by toothed whales is commonly computationally inefficient. We present an autoregression and correlation-based algorithm for detection and classification of odontocete clicks. The detection process consists of three steps: (1) detection and extraction of impulsive signals from PAM recordings, (2) cross-correlation of the extracted sounds with template signals, and (3) binary classification of detected clicks. The extraction of impulsive signals from background noise is based on automatic detection of outliers in an autoregression model of noise. The model settings can be adjusted to detect signals of certain length. The cross-correlation analysis involves the use of template signals of high signal-to-noise ratio, which aremanually identified and extracted from PAM data. Using the cross-correlationcoefficient as a criterion allows distinguishing echolocation clicks by sperm or beaked whales from other impulsive sounds. Finally, binary classification utilizes thresholds determined through the receiver operating characteristic analysis of an independent subset of manually labeled, extracted signals. The approach was tested for detection of sperm and beaked whales in PAM datasets recorded on the Northwest Shelf of Australia and demonstrated low false positive rates of 3%–5%.
Vibration response of a two-dimensional heavy fluid loaded plate with ABH stiffeners
Authors: Martins Daniel , Karimi Mahmoud , Maxit Laurent
Published: November 2023

Acoustic black holes (ABHs) are a promising passive-control approach to mitigate plate vibrations in various engineering applications. By creating a gradient in the flexural waves, an acoustic black hole can trap and dissipate these waves, thereby reducing the amplitude of the vibrations in the plate. The ABH is based on gradually decreasing elastic plate thickness (to trap) and utilizing a damping layer to dissipate the wave energy. This technique has been applied to various structures, and hereby it is proposed to apply it to the stiffeners, commonly used to reinforce structures to increase their stiffness and reduce their susceptibility to vibrations. The studied structure consists of a heavy fluid-loaded infinite plate periodically stiffened and excited by a line force, i.e., a two-dimensional model. In the developed model, the stiffeners are characterized by their flexural and torsional impedances and can be estimated by a finite element analysis. These impedances are then coupled with the analytical formulation of the fluid-loaded plate problem expressed in the wavenumber domain to obtain the spectral displacement. The effectiveness of the ABH-shaped stiffeners in mitigating the plate’s vibration is demonstrated by comparing against results from rectangular stiffeners.
Vibration control of a cantilever plate immersed in water using shunted piezoelectric patches
Authors: Cao Huong , Karimi Mahmoud , Williams Paul , Dylejko Paul
Published: November 2023

Minimizing structural vibrations is an important engineering requirement in many applications. This study theoretically investigates the vibration control of an in-water cantilever plate using piezoelectric patches and resonant shunt circuits (including a resistance R and an inductance L in series or parallel). To do this, an analytical model for predicting the point-forced vibration response of a fluid-loaded cantilever plate with two piezoelectric patches is developed. The electromechanical coupling factor and optimum values for R and L are then estimated by considering the dynamics of the system in short-circuit and open-circuit conditions. The effect of piezoelectric patch size, location and electromechanical properties on the vibration response of the plate is also investigated through numerical examples. The results from this study show that optimized piezoelectric patches could provide a significant vibration reduction for underwater applications.
Leveraging audio and music experience in a first-year engineering sequence
Authors: Smith Sarah R. , Thompson Benjamin
Published: November 2023

Recently, the introductory courses in Audio and Music Engineering (AME) at the University of Rochester have succeeded in attracting an academically diverse group of students, such that engineering majors often comprise a minority of those enrolled. Therefore, we see our mandate as balancing the need to prepare AME majors for subsequent courses while simultaneously engaging and supporting non-majors. To meet this challenge, we leverage students’ existing experiences with sound and music to introduce foundational concepts in acoustics, circuits, and programming in a project-based environment. In the fall, students complete a series of labs where they build and conduct experiments on sections of a guitar amplifier. Each lab emphasizes a key electronics concept, culminating in a completed amplifier that students can keep. Similarly, the spring semester centers around a series of MATLAB assignments, culminating in a short-time Fourier transform project where students investigate the properties of reverberant speech. In both classes, lectures are designed to provide students with the theoretical tools necessary to fully engage with these projects. In this presentation, we share a specific approach that has been successful for us in engaging non-majors while supporting majors in STEM courses and plan to provide associated open curriculum materials.
Laser-induced sonar: A promising approach for improved underwater acoustic sensing
Authors: Janapati Yellaiah
Published: November 2023

This study presents the characteristics of acoustic pressure impulses generated by nanosecond laser-induced filamentation (ns-LIF) of water, focusing on the spatial, temporal, and spectral domains. In the time domain, the peak-to-peak (Pk-Pk) overpressures increase with higher incident optical energy while the arrival time remains constant. Notably, linearly polarized pulses exhibit higher Pk-Pk overpressures than circularly polarized pulses. Acoustic measurements of ns-LIF in water demonstrate a linear correlation between filament size and incident laser energy due to multiple plasma sources along the optical beam propagation. Alongside the temporal information, the spectrogram visualizes broad-spectrum underwater acoustic pressure impulses ranging from 10 to 800 kHz, perpendicular to the optical beam propagation. The low-frequency instantaneous underwater acoustic signals generated by ns-LIF is ∼90 kHz, offering advantages such as extended propagation distances and reduced attenuation in water. In addition to the experimental investigation, finite element analysis is employed to visualize the propagation and interaction of underwater acoustic signals across various interfaces. This integrated approach provides valuable insights into the behavior and characteristics of underwater signals. Eventually, our findings demonstrate the successful development of remote laser-induced sonar technology.
Human auditory ecology: Extending hearing research to the perception of natural soundscapes by humans
Authors: Lorenzi Christian
Published: November 2023

A “natural soundscape” refers to the case where the contribution of acoustic events resulting from human activity can be considered as negligeable. As a consequence, natural soundscapes are only composed of biological sounds and geophysical sounds shaped by the specific way sounds propagate within the habitat under study. Within this framework, studying soundscape perception in humans aims at unveiling the relationship between the features of sound mixtures picked up at a given place and time by the peripheral auditory system of a human listener and the characteristics of the auditory percept evoked by these features. We will present a research program based on large and ecologically-valid acoustic databases recorded in protected areas aiming to (i) better understand the mechanisms involved in auditory perception of natural soundscapes; (ii) characterize and explain the effects of sensorineural hearing loss on perception of natural soundscapes; and (iii) assess the extent to which alterations in soundscape perception can be restored back to normal via hearing aids. This programme combines modelling and psychophysical methods to explore our ability to distinguish between habitat, time of day and season, to detect the presence of biological sound sources and to assess levels of biodiversity in the habitat.
A combined method for multi-channel active noise control based on online adaptive estimation and offline convolutional neural network
Authors: Xiang Qinxuan , Chu Yijing , Wu Ming , Yu Guangzheng
Published: November 2023

Multi-channel active noise control (ANC) has been widely used to attenuate low-frequency noise in relatively large spatial areas. Traditional multi-channel systems are achieved by optimizing the controller weights with adaptive algorithms that minimize the power of all error signals. However, nonlinearity in ANC systems can significantly degrade the performance of conventional adaptive algorithms, which is even more severe in multi-channel systems. Researchers suggested using neural networks (NN) to deal with the nonlinear problems. However, applying NN to multi-channelANC systems is challenging in real-time processing because of the high computational burden. Therefore, a multi-channel ANC method that combines NN and adaptive method is proposed. The proposed controller consists of both linear and nonlinear parts, where the linear part is estimated adaptively to track the change of primary noise in real applications while the nonlinear part is modeled offline with a small-scale convolutional NN (CNN). This method has the advantages of solving the nonlinear problem in ANC systems and achieving the capability in tracking primary noise source positions. At last, the performance of the proposed algorithm is verified through simulation experiments.
Graph signal processing is combined with deep learning for detection of damaged wind turbine blades
Authors: Pan Xiang , Zhang Chenhui
Published: November 2023

For early warning the damaged blade of wind turbines, an emission noise processing framework is proposed based on combination of Graph signal processing and Deep Learning. A microphone array is utilized to receive the noise emitted by the wind turbine blades. The weak abnormal signal from the damaged blade is enhanced by beamforming techniques. The enhanced signal is transformed into the graph domain by Graph Fourier Transform, from which the Mel filter bank features are extracted as inputs of a Multi-scale Feature Aggregation Conformer (MFA-Conformer) for damage detection. The MFA-Conformer combines Transformers and convolution neural networks (CNNs) to capture global and local features from the frequency or Graph domain. And the multi-stage aggregation strategy is utilized to exploit hierarchical context information. The reduction in the computational cost is achieved in the CNNs-based damage detection due to the real-valued features extracted from graph domain. The MFA-Conformer neural network is trained on the dataset which is created by applying data augmentation to the training samples. With the Mel filter bank features extracted from the frequency and graph domains, the MFA-Conformer neural network performs well in the five wind-farm data tests, with 2.55 % improvement in accuracy over the residual networks.
Recent progress in acoustic metamaterials with ventilation
Authors: Ang Linus Yinn Leng , Cui Fangsen
Published: November 2023

To develop sustainable cities, natural ventilation is being explored as one of the ways to reduce energy consumption and carbon dioxide emissions. Recently, acoustic metamaterials with ventilation have garnered attention for their potential to provide both ventilation and noise control. In addition, this class of acoustic metamaterials can be used as a machine enclosure for dissipating thermal load and reducing noise emission. This presentation focuses on the recent progress in acoustic metamaterials with ventilation over the last five years, highlighting three types: metamufflers, metapanels, and metacages. Furthermore, the challenges faced by metacages for real-world applications are presented.
Achieving stable convergence of neural networks for estimating acoustic field in uniform ducts
Authors: Dharanalakota Veerababu , Raikar Ashwin R. , Ghosh Prasanta K.
Published: November 2023

The ability of the neural networks as function approximators can be exploited to solve several governing differential equations. In this work, 1-D Helmholz equation is solved to predict the acoustic pressure in a uniform duct. Solving the Helmholtz equation across a range of frequencies, especially at higher frequencies is challenging as the loss function destabilizes the training process, thereby preventing it from converging to the true solution with the desired accuracy. To overcome this issue, a dynamic learning rate technique is proposed that helps to stabilize the training process and improve overall accuracy of the network. The efficiency of the method is demonstrated by comparing the results with a static learning rate method and the analytical solutions. A good agreement is observed between the predicted solution with dynamic learning rate and the analytical solution up to 2000 Hz. Without dynamic learning rate, the relative errors are observed tobe 2% and 58% at 500 and 2000 Hz, respectively, whereas they reduced to 0.6% and 0.1%, respectively, with the dynamic learning rate at the same frequencies. The proposed dynamic learning rate method is found to be effective for different types of boundary conditions.
Flow noise radiated from a cylinder above a plate
Authors: Tan Jiawei , Moreau Danielle , de Silva Charitha , Fischer Jeoffrey , Doolan Con
Published: November 2023

The flow noise of an infinite span circular cylinder has been well documented over the past decades. In reality, cylinder flows are rarely isolated from any nearby boundaries. The addition of a large flat plate to one side of the cylinder created an asymmetric configuration, termed as the cylinder above a plate (CAP). Examples include roof racks and rail pantographs. Flow diagnostics of a CAP have been lacking when compared to the baseline unbounded cylinders, while the corresponding noise measurements have been practically absent. Recently, the rigid CAP configuration was systematically tested in subsonic, air flow. Cylinders with various cross-sectionalshapes were tested. Microphone measurements were used to characterize the noise generated by a CAP, while particle image velocimetry (PIV) was used to characterize the cylinder wake. When the gap between the cylinder and plate was reduced, the amplitude of the tonal noise radiated from the cylinder flow generally reduced, while acoustic directivity pattern was heavily modified. The correlated flow structures were weakened and pushed away from the plate, which strongly suggested a modulation of the fluctuating forces exerted on the cylinder. By Curle’s acoustic analogy, this was related to the modified acoustic noise and directivity.
Speech communication in outdoor learning environments
Authors: Vossart Christian
Published: November 2023

Newton Central School (NCS) celebrates its 100th birthday this year. Its noise environment has evolved significantly over that time and is now dominated by road-traffic noise from the adjacent State Highway 16. Master planning for the redevelopment of NCS, to enable the school roll to be more than doubled, necessitates consideration of how noise emissions to the site can best be minimised and managed, particularly for outdoor learning areas. The transmission of road traffic noise across the site (up to 2043) is predicted and the methodology is detailed. The use of the local topography, locations, and arrangement of buildings and open space, and zoning of different types of outdoor activity to both mitigate and manage transmission is explored. The resultant levels of ambient noise achieved through different mitigation options are discussed via comparison with different sources of published design criteria for outdoor learning and other activities within open spaces. The results are also considered in terms of a signal-to-noise relationship. The relative benefits of reductions in noise for the end user/stakeholder are clarified with reference to the likely subjective perception of comparative changes in noise level. The application of lessons learned and the potential for further study are investigated.
Time domain virtual sensing method based on a rigid-sphere transfer function for active noise control headrests
Authors: Shinobu Naoki , Yoshimatsu Toma , Itou Hiroaki , Kozuka Shihori , Kamado Noriyoshi , Haneda Yoichi
Published: November 2023

Active noise control (ANC) is expected to be used in public transportation such as airplanes and trains. While using these applications, passengers prefer not to wear earphones or ear microphones, if possible, to reduce ear strain. However, conventional ANC systems require a physical microphone, which acts as an error sensor, at the ear position. To address this issue, a virtual sensing technique has been studied that uses a microphone mounted on a seat’s headrest to estimate the sound pressure at the ear position. In this study, we propose a virtual sensing technique that interpolates the sound pressure at the ear position using a spherical microphone array surrounding the head. This method improves robustness to variations in noise arrival direction using spherical harmonic coefficients without directional dependence. In general, the interpolation formula using spherical harmonic expansion is obtained in the frequency domain. By contrast, the proposed method designs the interpolation process as an IIR filter by considering the minimum phase and estimates the noise signal directly in the time domain, achieving the real-time processing required for ANC. The effectiveness of the proposed method in reducing noise was investigated for various noise arrival directions.
Unveiling weak auditory evoked potentials using data-driven filtering
Authors: Jacob Stefan , Koch Christian
Published: November 2023

Auditory evoked potentials (AEPs) are commonly used to objectively evaluate sound perception in humans. Close to the hearing threshold and for low frequencies, efficient filtering of AEP from other brain activities is of major concern due to weak potentials and the requirement of long averaging times. Filtered AEP data are well-interpretable and useful, especially in medical and psychological diagnostics. Here, we present two data-driven approaches for efficient AEP filtering. First, neural networks of different architectures trained for EEG denoising are used to extract weak late-response AEP for low-frequency and infrasonic stimuli. During the design of the networks, we leveraged knowledge of the specific characteristics of the expected AEP data. Second, a singular value decomposition (SVD) of EEG data is evaluated, attempting to create classifiers for the presence of weak late-response AEP modes. We anticipate that the evaluation of AEP with data-driven methods can support researchers and scientists, for example, with real-time evaluation and diagnosis of acoustic-induced discomfort.
Aeroacoustic and aerodynamic measurements of a ducted propeller
Authors: Li Jingang , Malkki Justin , Yauwenas Yendrew , Doolan Con , Moreau Danielle
Published: November 2023

The flexibility and wide range of possible applications in both civilian and military areas make unmanned aerial vehicles (UAVs) an object of continuous research. An important focus of such work is the propulsion system and ways of improving its efficiency. A ducted propeller is a common solution to increase the thrust and power efficiency of the propulsion system, which is especially beneficial for UAVs driven by electric motors due to their limited battery capacity; however, noise created by UAVs can not only annoy the public but may also reduce its acoustic stealth. Hence, the aim of this paper is to describe a test rig that can take aeroacoustic and aerodynamic measurements of both ducted and open propellers and present some initial experimental results. Both aeroacoustic and aerodynamic measurements were taken in an anechoic chamber with an arc of 6 ½ in. microphones to record noise level from different directions. The APC 12 × 8 propeller was used together with the SunnySky x2820 brushless motor.
Impression difference to vehicle interior sound between active and passive driving situation
Authors: Okabayashi Nawoki
Published: November 2023

In near future, autonomous vehicles are expected to be more popular due to the technology development. This transition from active to passive driving condition may change the driver’s impression to vehicle interior sound. And the interior sound improvement for autonomous vehicles should be done according to the difference. In this study, we investigated whether driver’s impression to interior sound changes or not according to the driving situation through subjective evaluation test using a driving simulator. In the test, an original driving simulator was prepared to reproduce identical sounds and conditions at both active and passive driving conditions. As the presented sounds, sound pressure level (SPL) decreased or increased sound at low, mid, or high frequency bands were reproduced with the original sound. Participants drove the simulator under various driving conditions including acceleration and deceleration and evaluated discomfort about the sound. As the result, low or high frequency SPL decreased sounds were evaluated to be more discomfort at passive condition than that at active condition. Especially this tendency became significant at the acceleration and deceleration condition. From these results, high or low frequency noise reduction was found to be important in the future autonomous vehicle development.
Tuning the acoustic characteristics of bottle plant garden
Authors: Gulia Preeti
Published: November 2023

This work presents a finite element study to compute the acoustic performance of a garden that consists of periodically arranged bottle plants. The purpose of this work is to achieve low- and high-frequency noise reduction using plastic waste bottles. A harmonic excitation is given at one end, and transmission loss is calculated as a function of frequency between the two ends of the computational domain. The result shows that bottle plants produce a high-frequency wide band (1300–2100 Hz) around Bragg's frequency as well as a low-frequency sharp narrow band at the resonance frequency (∼305 Hz) of the bottle. To achieve a wider band gap at low frequencies, water level in the bottles is kept at different levels. The result showed that placing bottles with various water levels next to one another causes a bigger band gap at low frequencies (255–360 Hz). As a result, the low-frequency band gap can be tuned by changing the water level in the bottles. Plants' ability to absorb sound further dampens it at specific frequencies. Utilizing the plastic bottle to form such a garden has a major environmental impact and can function as a visually pleasing area while promoting calm and tranquilly.
Directional active noise control for drones
Authors: Bi Hanwen , Abhayapala Thushara , Ma Fei , Samarasinghe Prasanga N.
Published: November 2023

Drones have become ubiquitous in various everyday applications, but their noise pollution remains an annoying issue. In this paper, we study the possibility of applying active noise control on drones with attached speakers. We propose the active noise control algorithms designed to iteratively calculate driving signals of speakers for canceling the outgoing noise from drones, specifically focusing on the blade passage frequencies within a directional spherical sector region. Two active noise control strategies are proposed: (i) minimizing the residual signal coefficients and (ii) minimizing the acoustic potential energy within the sector region. We derive update equations for two variables: (a) the loudspeaker weights and (b) secondary source spherical sector harmonics coefficients. Considering the power and loading limitations of drones, simulations are conducted under constraints of secondary source numbers to investigate the noise reduction performance with various secondary source setups. Simulation results demonstrate that the proposed method can effectively reduce the noise level over the directional sector region with a fast convergence speed.
Tonality masking system: Design and implementation of an industrial noise masking application
Authors: Beresford Tim , Cyril Max
Published: November 2023

A noise source that exhibits tonal qualities is often deemed to be more annoying than one which is broadband in nature. In environmental noise assessments, it is common to apply a penalty for tonality (typically up to +5dB). Tonality is often objectively classified as a function of the spectrum shape (typically in one-third octave bands), where a prominent band relative to its adjacent bands indicates the presence of tonality. A potential means of removing this tonality is to introduce masking noise, altering the spectrum shape to cover up the peaks. By adding targeted masking, in principle, it is possible to not only remove the tonality classification and penalty but also minimise the increase in overall noise level to less than a few decibels. This paper discusses the practical implementation of a tonality masking system for a low-frequency industrial noise emission problem occurring at neighbouring residential properties. The masking system was designed to detect tones generated by a large piece of factory equipment and calculate the optimum masking signal using custom-made software. The masking signal was reproduced through a subwoofer located inside the factory. With the system successfully commissioned, the resultant noise levels at the residential neighbours were no longer classified as being tonal.
Assessment of long-range distributed acoustic sensing (DAS) capabilities in controlled environments
Authors: Sidenko Evgenii , Collet Olivia , Gavrilov Alexander , Duncan Alec J. , Erbe Christine , Lebedev Maxim , Tertyshnikov Konstantin , Gurevich Boris , McCauley Robert , Pevzner Roman
Published: November 2023

Distributed Acoustic Sensing (DAS) is an emerging technology enabling the recording of disturbances along fiber-optic (FO) cables with a wide range of applications, such as monitoring marine fauna, anthropogenic activities, and ocean climate. Despite the extensive research on DAS technology, its long-range capabilities have not been structurally studied yet. We present results of a sequence of purposefully designed experiments of DAS capabilities in (1) a laboratory, (2) a pool, and (3) a marine facility. To simulate long cables, we use combinations of FO coils 10–200 km in length. In the laboratory, realistic strain signals are simulated by an FO stretcher. In the pool, realistic acoustic signals are transmitted by an underwater speaker. At the marine facility, a combination of playback and real sound sources is used. Simultaneously deployed hydrophones allow DAS calibration and performance assessment. In this series of experiments, we measure internal noise, compare different DAS equipment, and successively optimize acquisition parameters for each interrogator performing at different, long sensing ranges in increasingly realistic environments. We show that long-range capabilities are strongly dependent on DAS settings (optical power, pulse repetition frequency, gauge length, pulse width) and vary between different interrogators.
A grating lobes suppression method for a steerable parametric array loudspeaker
Authors: Fan Fanyi , Zhu Yunxi , Yang Jun
Published: November 2023

A parametric array loudspeaker (PAL) is a highly directional sound source with small aperture size. To achieve accurate sound projection, the steerable PAL is implemented by the use of the phased array technology. In this paper, the sound field model based on the Westervelt equation of a practical steerable PAL is presented, and a quasi-linear approximation is adopted to obtain the spatial sound pressure distribution. By applying the phased array technology, the audio beam can steer to the target direction. However, the grating lobe arises when the transducers are spaced more than half a wavelength, which disturbs the effect of beam steering. We further propose the grating lobes suppression method and apply it to the steerable PAL. Simulation results validate the performance of the proposed method.
Acoustic metaliners for insulating noise in a duct with varying cross-sectional area
Authors: Kim Dohaeng , Jeon Wonju
Published: November 2023

We propose a sound-insulating acoustic metaliner for a duct with varying cross-sectional area with consideration of the flow that varies along the direction of flow and is not a fully-developed. The metaliner comprises an array of unit cells based on two different types of Helmholtz resonators and installed on the duct wall to preserve ventilation performance. To consider the effect of flow on the sound insulation performance of the metaliner, we establish an effective impedance model in term of the friction velocity, enabling the consideration for flows that are not fully-developed. The geometrical parameters of unit cells of the metaliner are designed individually considering the flow around each unit cell. The sound insulation performance of the designed metaliners for different flow speeds with the target frequency of 900 Hz is verified experimentally.
Towards a yardstick of spatial impression: Psychophysical experiments using virtual piano stimuli
Authors: Ishimura Fusako , Trevino Jorge , Tanaka Masaru , Shiozawa Yasuo
Published: November 2023

A rich “spatial impression” is an important factor in the product value of musical instruments. However, it also represents a development challenge since there is no established method to measure and control it. We introduce a novel yardstick for spatial impression, changing tacit knowledge into a measurable property. We focused on the difference in spatial impression between digital pianos and grand pianos, and conducted psychophysical experiments using piano sounds to identify the features that contribute to grand pianos’ spatial impression. We used multiple virtual stimuli which are created by varying physical parameters and conducted the experiment in a virtual environment including head-tracking from a VR headset. This allowed us to find a trend in the spatial impression and identify a physical parameter that correlates to the perceptual results of the experiment. This parameter, “phase entropy,” denotes the time complexity of the interaural phase difference. The correlation coefficient between the psychophysical experiment results based on virtual stimuli and the phase entropy was 0.8752. In addition to the virtual stimuli, we confirmed the correlation between perceptual score and phase entropy in an experiment using actual piano recordings; the correlation coefficient in this case was 0.6500.
Wavenumber-frequency relationships in the cochlea: Measurements and models
Authors: Alberts Gabriel , Puria Sunil
Published: November 2023

A fundamental characteristic of cochlear mechanics is the traveling wave—a transverse wave which propagates from base to apex along the basilar membrane. Experiments and models have shown that its wavenumber (2π/wavelength) increases with stimulus frequency for a given membrane place, linearly at first then quadratically as the stimulus frequency approaches the best frequency (BF; Puria and Steele, 2008, The Senses). The wavenumber-frequency relationship (WFR) beyond the BF in experiments and models remains to be understood. We used finite-element models of gerbil and mouse cochleae to calculate the WFR to frequencies well above the BF. Our models replicated previous findings of the WFR increasing linearly in the long-wave region then quadratically in the short-wave region, but the relationship subsequently turned linear again near the BF region and continued this way at higher frequencies. We hypothesize that this linear increase is due to viscous damping in the cochlea which continues to dominate the response well beyond BF. There is no sign of a mass dominated region in the WFR suggesting that there is no harmonic oscillator resonance at least up to a few octaves above the BF. [Work supported by the Amelia Peabody Scholars Fund and NIDCD R01DC07910, F31DC021079, and T32 DC000038.]
Impact of ultrasonic inertial cavitation on the pancreatic tumor stiffness in mice
Authors: Rohfritsch Adrien , Drainville R. A. , Renault Gilles , Bibaki Giovanna , Urro Sarah , Giammarinaro Bruno , Wang Litan , Ngo Jacqueline , Prat Frédéric , Lafond Maxime , Lafon Cyril
Published: November 2023

Pancreatic ductal adenocarcinoma (PDAC) is among the fastest-growing cancers and is predicted to become the second leading cause of cancer-related deaths worldwide by 2030. Ultrasound-induced inertial cavitation (IC) is an emerging therapeutic strategy with promise for treating patients with unresectable tumors. However, the physical impact of IC on tumors remains unclear. In this study, we used orthotopic murine models of pancreatic cancer and employed passive elastography to measure elasticity before and after applying IC to the whole tumor volume. The IC was generated using two focused confocal transducers (center frequency, 1.1 MHz). The output level was adjusted with a real-time feedback loop based on broadband signal acquired with a passive cavitation detector. Cavitation clouds were visualized during treatment using an imaging probe. The results from eight treated mice showed a 24% decrease (p < 0.05) in tumor stiffness after the IC treatment, indicating that the chosen IC sequence can soften the tumor environment. After sacrifice, we utilized second-harmonic imaging microscopy to visualize the collagen network within the tumor, a known contributor to tissue stiffness, and correlated various features of this network (length, width, curvature) with the measured elasticity.
Decoding the hidden sounds from Tornadoes
Authors: Elbing Brian , Alexander Aaron S. , KC Real
Published: November 2023

Tornado Alley in the United States produces the largest tornadoes in the world, but the majority of tornado related deaths in the United States occur to the east of Tornado Alley. This is because that region has hilly terrain that limits the use of weather radar, which is responsible for the significant improvements in tornado warnings over the past 40 years. This is a growing problem as Tornado Alley appears to be shifting eastward. An alternative method is to use infrasound (sound at frequencies below human hearing) emitted during the formation and life of a tornado to improve warnings. The fluid mechanism(s) responsible for the sound needs to be identified to properly interpret the received signals. This presentation will report on recent laboratory experiments aimed at investigating potential fluid mechanisms as well as field observations with measurements from tornadoes. [This work was funded, in part, by the Gordon and Betty Moore Foundation under grant GBMF11559 (doi.org/10.37807/GBMF11559).]
Characterization of acute and subacute immune response to boiling histotripsy ablation of pancreatic adenocarcinoma
Authors: Khokhlova Tatiana , Wang Yak-Nam , Son Helena , Xu Zhen , McGinnis Reliza , Fite Brett , Kare Aris , Ferrara Katherine , Padilla Frederic
Published: November 2023

Boiling histotripsy (BH) is a cavitation-based pulsed focused ultrasound method of mechanical tissue disintegration. When applied to tumor ablation, BH was shown in a number of preclinical studies to stimulate antitumor immune responses, with the extent and dynamics depending on the tumor microenvironment. In this work, we assessed the response of pancreatic ductal adenocarcinoma (PDAC)—an immunologically “cold” tumor—to BH ablation. C57BL/6J mice (n = 6 per group) were bilaterally subcutaneously grafted with KPC-derived mT4 cell line in the hind limbs. When one of the two tumors reached 8 mm, 80% of its volume was ablated with BH (1.5 MHz, 3 ms pulses, 1% duty cycle, 450 W power, 15 pulses/point). The tumors, inguinal lymph nodes and spleens were harvested at 1-, 3-, and 6-day time points and processed for immune phenotyping through flow cytometry, histology, and immunohistochemistry. At earlier time points, the response within the tumor was dominated by neutrophils, and by day 6—by inflammatory monocytes both in treated and contralateral sides versus sham. Transient increases in B cells, neutrophils, NK, NKT cells, and monocytes were observed in the ipsilateral lymph nodes and in spleens on day 3, and mostly subsided by day 6. These data will inform further studies in optimization of combination therapies for PDAC. [Work supported by Focused Ultrasound Foundation.]
Sonic boom near field analysis of a Mach 5 wave-rider configuration
Authors: Graziani Samuele , Viola Nicole , Fusaro Roberta
Published: November 2023

The following paper discuss the near field sonic boom results obtained with CFD simulations regarding a Mach 5 wave rider configuration derived from the STRATOFLY heritage. Sonic boom near field have emerged as a vital tool for the mitigation and understanding of the impact of supersonic and hypersonic aircraft configurations. The work done discusses the major consideration in the CFD approach for the flow field simulations in the vicinity of the aircraft, including grid generation techniques based on the NASA sonic boom predictions workshop carried out between 2014 and 2020 and the results obtained for different flight conditions and operations. The near field simulation necessitates of accurate predictions of shock wave propagation generated by the aircraft, employing the high-fidelity numerical schemes and turbulence models. These results will be the input for our propagation tool that manage to propagate the shocks from the aircraft to the ground. This work is carried out within the MORE&LESS project, that is an EU-funded project and has the aim to investigate the environmental impact of supersonic aircraft through multi-fidelity simulations and test campaigns for creating multidisciplinary holistic framework for the evaluation of the future supersonic aircraft, trajectories, and operations.
Computational aeroacoustics and phase-conjugation technique for localizing flow-induced sources
Authors: Mimani Akhilesh , Kumar Shubham
Published: November 2023

This paper presents a framework comprising computational aeroacoustics (CAA) solvers and a numerical phase-conjugation technique to localize flow-induced noise sources generated by bodies immersed in low Mach number flows. Two test-cases were considered, namely, flow over a two-dimensional (a) circular cylinder at Reynolds number Re =150 and Mach number M = 0.2 and (b) NACA-0012 airfoil at Re = 5000 and angle of attack (AoA) α = 5 deg. The CAA simulations were carried out in OpenFOAM wherein the two-dimensional unsteady, incompressible Navier–Stokes equations was solved using either the pressure-implicit splitting of operators (PISO) algorithm or large eddy simulation (LES). The near-field aerodynamic sources were extracted in terms of the unsteady Lighthill stress tensor terms, following which the far-field acoustic data were computed on boundary nodes using different methods which include the numerical solution of the Lighthill equation, Curle’s analogy, and Ffowcs Williams and Hawkings (FWH) analogy as well as linearized Euler equations (LEE). Next, the frequency-domain phase-conjugation (PC) method was implemented in the finite-element (FE) based COMSOL software to reconstruct the radiated acoustic pressure field, whereby the dipole source location was readily identified by pair of focal spots at the cylinder or at the airfoil trailing-edge (TE).