bluuebunny/crossref_metadata_2025 huggingface dataset:
Double phononic crystal lens-based enhancement of underwater power transfer
Authors: Allam Ahmed , Sabra Karim G. , Erturk Alper
Published: November 2021

Acoustic waves are widely used for underwater communication and also investigated for power transfer owing to their low attenuation compared to electromagnetic waves. We investigate enhancing the performance of an underwater Acoustic Power Transfer (APT) system using Gradient-Index Phononic Crystals (GRIN-PCs). The GRIN-PCs consist of air inclusions in a 3D-printed polymer and are used to construct 3D acoustic lenses capable of collimating and focusing acoustic waves. The lenses are used to improve the directivity of a point source transmitter and focus the acoustic waves at a point receiver to reduce spreading losses in the APT system. The developed lenses allow for using lower frequency transducers to transmit power, hence reducing wave attenuation, and enhancing the efficiency of the system. The enhancement is verified experimentally using hydrophones as point transmitters and receivers in a double-lens system. Additionally, the lenses were used to enhance the performance of 100 kHz piezoelectric transducers with limited directivity, increasing the output power by an order of magnitude. Numerical models based on the finite element method were used to study the effect of varying the separation distance, lens aperture, and frequency on the pressure field. The developed APT concept could find applications for power delivery to wireless devices used in ocean monitoring, underwater navigation, marine life tracking, among others.
3D printed fibrous porous structures with enhanced noise reduction properties
Authors: Johnston Will , Kankanamalage Pulitha G. , Pathak Siddharth , Drouin Mary , Sharma Bhisham
Published: November 2021

Additive manufacturing allows the cost-effective fabrication of cellular porous structures with tailorable geometries. Structures with small pore sizes offer improved acoustical performance; however, they often result in increased structural weights and are difficult to produce using low-cost additive manufacturing methods. Here, we leverage our recent work demonstrating the fabrication of fibrous structures using 3D printing, to develop multifunctional porous structures with enhanced acoustical properties. Our method allows the addition of fibers to a structural host, which helps improve the acoustical performance without a significant weight or flow-reduction penalty. In this presentation, we outline the fabrication method and study the effect of adding fibers to the acoustical performance of porous structures with periodic gyroid unit cells. The effect of fibers on the acoustical impedance and flow resistance is studied using an impedance tube and a flow bench, respectively. We then use an inverse characterization method to analyze the effects of changing fiber and structural parameters on the acoustical performance. Our results show that adding fibers to porous host structures can drastically improve their broadband noise reduction potential.
Perception of checked tones in Xiapu Min
Authors: Chai Yuan
Published: November 2021

Xiapu Min is a variety of Min Chinese spoken in Xiapu, Fujian, China. The language has seven tones, two of which (T53 and T21) are checked tones that only appear in syllables with a glottal stop coda (Chai and Ye, 2019). Compared with their unchecked counterparts, checked tones have distinct f0 contours, glottalization at the end of the syllable, and are of shorter duration. In this study, we investigate whether those acoustic features are used by listeners of Xiapu Min to identify whether a tone is checked or not. We ran a forced-choice identification task with resynthesized audio stimuli. Stimuli consisted of a natural unchecked token resynthesized with five distinct f0 contours. Each vowel was further modified to have a short versus long duration and presence versus absence of glottalization. The results indicate that the listeners are more likely to identify a stimulus as having a checked tone when it has a high-falling f0 contour (similar to checked T53), shorter duration, or glottalization, among which the duration has the largest coefficient. Thus, all three phonetic parameters found in checked tone production also influence checked tone identification. However, duration is more likely to matter for the identification of checkedness than f0 or glottalization.
Using RMS differentials for robust onset time estimation of impulses
Authors: Jerome Trevor W.
Published: November 2021

Various methods exist for estimating the precise onset time of broadband impulses in a time-domain signal. The method presented here offers a high robustness, with speeds relativley equal to or surpassing currently existing methods. The method is capable of dealing with impulses that have been corrupted by dispersion. Onset time correlates well with the maximum of the lower envelope bound curve of the derivative of the RMS in low-noise signals. In noisy signals, the onset time is found using the samemethod and a noise correction procedure can be applied for more precision.
Residual physical modeling and semi-supervised source localization
Authors: Bianco Michael J. , Gerstoft Peter
Published: November 2021

Source localization in reverberant environments remains an open challenge which ML techniques have shown promise in addressing. Real-world acoustic environments contain irregular boundaries, scattering, and diffracting elements (e.g., furniture and uneven surfaces) which are impractical to model using acoustic propagation software. We develop a hybrid approach to acoustic source localization which utilizes both analytical, signal processing-based localization, and machine learning (ML) to provide a data-driven source localization model. In this approach, the output of an analytical source localization model (e.g., SRP-PHAT or MUSIC) is augmented by a neural network (NN) system. This augmented system consists of a variational autoencoder and localization network, which is designed to correct the analytic estimate. The networks are trained via semi-supervised learning, on both labeled and unlabeled inputs. The NNs in this approach parameterize stochastic functions, which facilitate a statistically principled learning approach via variational inference (VI). The stochasticity also helps quantify source location uncertainty under the VI approximate posterior. For simulated and real acoustic data, the hybrid approach generalizes better and is more efficient than ML or analytic approaches alone.
Interferometric method of the signal processing in shallow water
Authors: Pereselkov Sergey A. , Kuz'kin Venedikt , Kaznacheeva Elena
Published: November 2021

The interferometric signal processing method for localizing a broadband moving sound source in shallow water is proposed and studied theoretically and experimentally in the paper. The field of a moving sound source creates in waveguide a stable interference pattern of the intensity distribution (interferogram) in the frequency-time domain. Sound intensity is accumulated along interference fringes over the observation time. The two-dimensional Fourier transform (2D-FT) is applied to analyze the interferogram. The result of the 2D-FT of the interferogram is called the Fourier-hologram (hologram). The mathematical theory of hologram structure is developed in the present paper. It is shown that the hologram allows to coherently accumulate the sound intensity of the interferogram in a relatively small area as focal spots. The presence of these focal spots is the result of interference of acoustic modes with different numbers. The main result of our paper is a simple relationship between the focal spots coordinates on the hologram and the source range, velocity, and motion direction. The proposed interferometric signals processing method for the source localization is validated using the data of acoustic experiment and numerical modeling. [This research was supported by the RFBR (19-29-06075, 19-38-90326).]
Using energy flux methods to derive a 3D ocean acoustic propagation model
Authors: Langhirt Mark A. , Holland Charles W. , Lin Ying-Tsong , Martinelli Sheri , Brown Daniel C.
Published: November 2021

The energy flux model is a direct source-to-receiver calculation that avoids the need for finding eigenvalues, but it averages out the modal interference structure as originally derived. It has been shown possible in the two-dimensional model to include the near-neighbor modal interference that resolves large-scale caustic features and shadow zones. So far limited work has been done to develop three-dimensional energy flux models for ocean acoustic propagation, but such a model may have significant computational advantages in complex environments or at high frequencies. We present current progress towards developing three-dimensional underwater acoustic propagation models that have been derived using energy flux principles. In particular we will discuss a vertical normal mode and horizontal energy flux model used to solve for the acoustic propagation in a wedge environment.
Rayleigh scattering of a cylindrical sound wave by parallel, infinite cylinders
Authors: Baynes Alexander B.
Published: November 2021

Scattering of sound by a target can be described as a wave radiated by virtual point sources inside the target. In the Rayleigh scattering regime, the strength of the virtual sources can be calculated analytically, and the number of linear sources is finite. When a target is located close to the ocean surface or another reflecting boundary, reflections of the incident and single-scattered waves from the boundary lead to multiple scattering from the target, with the target being insonified by nearby virtual sources. The virtual source method has recently been applied to study low-frequency acoustic fields in the vicinity of cylindrical targets near a pressure release surface or a hard bottom. This method is extended here to study the acoustic field in the near- and far-field of parallel cylindrical targets for arbitrary positions of the sound source. Multiple scattering solutions for scattering from soft, hard, and fluid targets are considered.
Scale-partitioned differential modeling of large-amplitude acoustic streaming
Authors: Orosco Jeremy , Friend James
Published: November 2021

Classical techniques for modeling acoustic streaming rely on expansion of the flow about the relative slowness of the streaming velocity in comparison to the particle velocity. Rayleigh pioneered this approach nearly a century and a half ago for deducing streaming equations from the Navier-Stokes governing equations. Modern acoustofluidics applications do not generally admit the order of magnitude separation between flow components that is required in classical “slow streaming” approaches. We outline a theoretical technique that provides greater generality by using drastic spatiotemporal scale disparities to decompose the field equations. We achieve this with scale-partitioned differential operations. The framework is useful in general for modeling continuous nonlinear systems. We first provide brief examples of applying the framework to various media before exploring its use in the area of acoustofluidics specifically. We analyze large-amplitude (“fast”) bulk acoustic streaming in a one-dimensional setting. The resulting model explains empirically observed characteristic nonlinear streaming phenomena. From the model, we deduce a variety of bulk streaming properties, including a simple, algebraic upper bound on the maximum achievable streaming velocity in relation to the acoustic forcing. A comparative analysis is undertaken using experimental data from the recent literature.
Vessel noise modelling around the Port of Prince Rupert, British Columbia, and the potential effects on marine mammal listening distance
Authors: Ramsey Elizabeth , Warner Graham , MacGillivray Alexander
Published: November 2021

Underwater sound was modelled around the Port of Prince Rupert, British Columbia. The waters around the port region contain major international shipping lanes and important habitat for marine species, many of which require a quiet environment. Underwater noise calculations were carried out using JASCO's Acoustic Real-Time Exposure Model for In-motion Sources (ARTEMIS), a cumulative noise exposure and noise mapping model. Vessel traffic for three Periods were modelled using Automatic Identification System (AIS) vessel position reports from 2019: 1 to 31 January, 15 Jun to 15 July, and 15 September to 15 October. Vessel source levels were modelled using the JOMOPANS-ECHO reference spectrum model (MacGillivray and de Jong, 2021). Ambient noise was modelled using the Wind and Rain Ambient Sound Propagation (WRASP) model (Ainslie, 2010). Sound propagation loss was precomputed using the normal mode code, ORCA (Westwood et al., 1996). Vessel traffic projections for 2030 were created with AIS data from 2019 and 2020 to simulate underwater sound levels for 2030. Potential effects on marine mammals was assessed by calculating the relative reduction in distance (listening distance ratios) to which they could communicate, forage, and detect predators due to vessel noise. Listening distance ratios were assessed for 2030 using 2019 as a baseline.
International Year of Sound 2020–2021: Main events and achievements
Authors: Burgess Marion , Taroudakis Michael , Stinson Michael R. , Polack Jean-Dominique
Published: November 2021

The International Year of Sound 2020–2021 includes activities organized by the IYS Steering Committee, ICA member societies, international affiliates and individual organizations. The web page www.sound2020.org, is the primary contact for the IYS and receives more than 3500 visitors per month. The opening was held in Paris at the Grand Amphitheatre of the Sorbonne on 31 January 2020. A film “Sounds of our Life” was launched and is also available on Youtube. An international student competition involved over 15 000 students and attracted excellent contributions. The international scientific conferences included outreach and promotions for the IYS. Despite the restrictions due to COVID-19, ICA members maintained their enthusiasm and contributed an amazing range of innovative virtual activities and resources. Additional outreach included various media items and podcasts. The IYS has encouraged further collaboration with institutions including the WHO, the CHC and groups dealing with sound. This will eventually will strengthen the acoustics community into the future. Information on the activities and all the resources are freely available from the website and will remain as a legacy of the IYS. Despite the challenges of 2020 and 2021, the efforts of so many have shown the resilience and innovation of the acoustic community to enhance the understanding worldwide of the importance of sound.
Acoustical Society of America and the International Year of Sound
Authors: Jones Keeta
Published: November 2021

In this presentation, I will discuss how the Acoustical Society of America (ASA) celebrated the International Year of Sound. To stimulate the understanding and awareness of the important role that sound plays in all aspects of society, ASA produced short acoustics-themed videos, offered virtual acoustics demonstrations, presented online speakers, arranged a special issue of Acoustics Today, hosted a Twitter chat for the Journal of the Acoustical Society of America (JASA) and more. ASA education and outreach efforts will continue to improve and motivate the public to explore sound.
Strengthening the link between the ASA and the Spanish-speaking community
Authors: Jaramillo Ana M. , L'Italien Zachery O.
Published: November 2021

This presentation will discuss the efforts of the Spanish Speaking Acousticians in the Americas regional chapter over the past two years of the International Year of Sound to foster stronger connections between the ASA and the Hispanic community. An overview of presentations, events, collaborations, and other activities will be shared, as well as commentary on current challenges for acousticians in Latin America, recent progress, and how the ASA and the SSA can serve as an invaluable resource for the region.
Noise elicits the Lombard effect in midshipman mating vocalizations
Authors: Juanes Francis , Brown Nicholas , Halliday William D. , Balshine Sigal
Published: November 2021

Anthropogenic noise pollution is an emerging global threat to fish populations. Among a suite of deleterious effects, noise can potentially impede reproductive success in some fishes by masking their mate advertisement vocalizations. Using the plainfin midshipman fish (Porichthys notatus), a marine toadfish that produces a distinctive “hum” during courtship, we investigated how noise affects male vocalizations and spawning success in the wild. We recorded nesting males for three days and measured the frequency, amplitude, and duration of their vocalizations before, during, and after exposure to artificial noise (a c. 118-Hz tone). We also counted eggs in nests exposed to 10 days of artificial noise versus control nests that were not exposed to artificial noise. Males exposed to noise reduced the number of vocalizations they produced, reduced the frequency of their vocalizations, and increased the amplitude of their mating hum (Lombard effect). However, chronic noise exposure did not clearly affect spawning success, suggesting that the Lombard effect allowed males to sustain clear advertisement signals when competing with the relatively weak artificial noise source.
Predictable variability in humpback whale (Megaptera novaeangliae) song acoustics and potential masking of songs by anthropogenic noise
Authors: Perazio Christina E. , Dolan Madison , Johnston Ashley , Lyytikainen Sidney , Mercado Eduardo
Published: November 2021

Past analyses of humpback whale songs emphasize the flexibility with which whales change their songs across years. Acoustic measurements of song provide a way to systematically assess changes in songs and to predict humpbacks’ ability to adapt to changing soundscapes. Singers concentrate energy at predictable frequencies while continuously adjusting song acoustics. Analyses of songs from the Southeastern Pacific and Central North Pacific stocks (2013–2019) were used to characterize variations in peak frequencies. Preliminary results showed that humpbacks consistently concentrated energy in 3–4 frequency bands, suggesting that this is a universal feature of song production, and that singers may be less flexible in their ability to modify songs than has been assumed. Frequency use was also compared across different locations that vary in boat traffic. Initial findings revealed a negative association between peak frequency and the “noisiness” of a location. Examining patterns of variability in song acoustics may reveal an impact of anthropogenic noise on singing behavior. Predicting how increases in ocean noise may affect song is critical because whales are ecosystem engineers on a global scale. The extensive geographic and temporal coverage of these analyses adds a novel piece to this conservation puzzle.
Modeling Chirp SONAR returns due to random scatterers in sediment volum
Authors: Tang Dajun
Published: November 2021

The goal is to simulate time domain signals received by a subbottom profiling SONAR. While such SONAR systems are widely used and data from which are employed to interpret subbottom features and structures, there is a lack of modeling capability to simulate the SONAR returns scattered by random subbottom layers and sediment heterogeneity. Such a modeling capability is desirable to help make SONAR data interpretation from qualitative toward more quantitative. A two-way forward- and backward scatterer model is developed that is based on the mode coupling approach in a two-dimensional setting followed by Fourier synthesis to obtain time-domain signals. Numerical examples will be given to highlight the model capability, including cases with rough subbottom interfaces and random distribution of sound speed and density variations.
Joint estimation of water-column and seabed properties by inversion of modal-dispersion data
Authors: Dosso Stan , Bonnel Julien
Published: November 2021

This paper considers the joint estimation of water-column sound-speed profiles (SSP) and seabed geoacoustic models through Bayesian inversion of modal-dispersion data (arrival time as a function of frequency from warping time-frequency analysis). The inversion is formulated in terms of separate trans-dimensional models for the water column and seabed to intrinsically parametrize each according to the information content of the data. An efficient reversible-jump Markov-chain Monte Carlo algorithm is applied to estimate marginal posterior probability profiles, quantifying the resolution of SSP and seabed structure. Measured and simulated dispersion data, as well as varying levels of prior information, are considered to examine the ability to estimate water-column and seabed profiles, and to investigate relationships between these.
Estimating seafloor compressional sound speed using a long towed horizontal line array
Authors: Uzhansky Ernst , Makovsky Yizhaq , Katsnelson Boris , Copel Shelly , Kazaz Tom , Gadol Omri
Published: November 2021

The methodology and results of estimations of seafloor compressional sound speed along with sound speed gradient in a compacting passive margin basin (offshore Israel) setting using standard multichannel seismic data (35 Hz peak frequency, 7200 m long array with 576 hydrophones) is presented. Geo-acoustic inversion technique with three matching parameters: (1) compressional sound speed at the water-sediment interface c0; (2) constant positive velocity gradient K; and (3) thickness of the sub-bottom layer with a constant velocity gradient H2 was used for estimations. The model considered consists of a water layer with a velocity that varies according to the season of data acquisition, lying above a layer in which velocity increases linearly with depth. Estimated c0 and K assessed for bottom depths of 1000–1350 m, varied from 1500 to 1600 m s−1 and from 0.7 to 0.9 m s−1 per m, respectively, and tend to increase with bottom depth. It was also verified that there is no inter-dependence in the estimation of the different parameters. The proposed method allowed to make assessments of relatively low sound speed speeds at water-sediment interface, where conventional refraction-based methods are not applicable due to very high critical distance of the head waves.
Estimation of parameters of moving nonlinear internal waves using spectrogram of sound intensity fluctuations due to mode coupling
Authors: Jiang Yanyu , Grigorev Valery , Katsnelson Boris
Published: November 2021

In this paper, results of experiment ASIAEX in the South China sea are considered. Episodes are analyzed when soliton-like nonlinear internal wave moves during ∼6 h approximately along acoustic track ∼30 km; from the source to receiver, where depths of the sea is ∼350 and ∼120 m correspondingly. The source, placed near the bottom, transmitted pulses (M-sequences) with the frequency 224 Hz. Spectrogram of intensity fluctuations calculated on the base of theory of authors [Grigorev et al., J. Ascout. Soc. Am.140(5), 3980–3994 (2016)] shows that peak frequencies in spectrogram correspond to the most strongly coupling pairs of modes: in given case 2-3, 3-4. Due to narrowing channel velocity V of moving soliton should decrease; note that the corresponding change of the predominating frequency as a function of position of soliton (or time) was observed. It is shown that temporal dependence of soliton’s speed can be the fitting parameter to estimate this dependence using comparison of experimental data and results of modeling. The corresponding procedure gives values of V changing from 1.8 to 0.8 m/s, what is in a good agreement with satellite data, obtained for the same event. [Work was supported by RFBR, Grant 20-55-S52005.]
Cavitation is the primary mechanism for stone dusting in holmium:YAG laser lithotripsy
Authors: Chen Junqin , Ho Derek , Xiang Gaoming , Sankin Georgy , Preminger Glenn , Lipkin Michael , Zhong Pei
Published: November 2021

Ureteroscopy with holmium(Ho):YAG laser lithotripsy (LL) is the primary treatment modality for kidney stone patients. Despite this, the mechanism of stone dusting in LL is unclear. In this work, we treated 6 × 6 mm cylindrical BegoStone phantoms using 0.2–0.4 J and 20 Hz at various fiber-to-stone standoff distances (SD) either in water or air with perpendicular fiber orientation; the latter eliminates the contribution of cavitation. The laser fiber was advanced at different offset distances (OSD) from a flexible ureteroscope tip to alter LL-induced bubble dynamics. Furthermore, stones were treated in parallel fiber orientation to minimize thermal ablation while isolating cavitation damage. Our results demonstrate that stone damage in water is 2.5- to 90-fold of those produced in air. At OSD = 0.25 mm when the bubble collapsed away from the stone surface due to the presence of the scope tip, stone damage was greatly reduced to the level in air. Moreover, the average crater volume produced by parallel fiber orientation after 100 pulses was comparable with those produced by perpendicular fiber within SD = 0.25–1 mm. Altogether, we conclude that cavitation is the primary mechanism over photothermal ablation for stone dusting in Ho:YAG LL.
Progression of hemorrhagic kidney injury from burst wave lithotripsy exposures
Authors: Wang Yak-Nam , Maxwell Adam , Chen Tony T. , Cunitz Bryan W. , Thiel Jeff , Hunter Christopher , Leotta Daniel , Williams James C. , Liu Ziyue , Arora Akshit , Vohra Ravneet , Lee Donghoon , Kreider Wayne
Published: November 2021

Burst wave lithotripsy (BWL) is a new non-invasive treatment for comminuting kidney stones. Although exposure parameters used in current clinical trials have produced negligible renal injury in preclinical pig studies, it remains of interest to understand how quickly injury accumulates, should it occur. BWL treatments lasting ≤30 min were delivered to 36 sites in 20 kidneys of 11 pigs. Treatments at 350 kHz utilized pulses with supra-clinical 8–9 MPa peak negative pressure, 20 cycles/pulse, and a pulse repetition frequency (PRF) of 10 or 40 Hz. Real-time monitoring was performed with B-mode and Doppler ultrasound to identify the presence and duration of cavitation activity, which has been correlated with the onset of injury. After treatment, kidneys were excised for magnetic resonance imaging (MRI) within 3 h of euthanasia. MRI was used to quantify the volume of any hemorrhagic injury. For sites with injury at 40 Hz PRF, the average (n = 5) injury volume increased with the number of BWL pulses (72, 720, 7200, or 72 000 pulses) delivered with cavitation. Notably, the rate of lesion growth slowed above 7200 pulses while all lesion volumes were smaller for equivalent cavitation exposures at 10 Hz PRF. [Funding support by NIH P01-DK043881, K01-DK104854.]
Input-output analysis of fluid–structure interaction to optimize stone breakage in burst-wave lithotripsy
Authors: Cao Shunxiang , Colonius Tim , Maxwell Adam , Kim Ga Won , Sapozhnikov Oleg A. , Bailey Michael R.
Published: November 2021

Burst-wave lithotripsy is a non-invasive treatment of kidney stones using short pulses of focused ultrasound. In this talk, we present the use of input-output analysis to optimize the design and control of a multi-element array transducer to achieve optimal stone breakage. The analysis is based on a linear fluid-structure coupled system that maps the acoustic forcing from individual elements to the stress in a stone of assumed shape, size, and composition. We determine the optimal frequency and optimal distribution of the phase and amplitude across the aperture by maximizing a cost function that represents the strain energy in stone. The optimal parameters are obtained by applying a state-of-the-art, randomized singular value decomposition (SVD) to the discrete linear operator. The results show that carefully controlling the relative phase and amplitude between elements can increase the strain energy (by 2-3 times in certain cases) compared to a uniform distribution under the same input energy. This suggests that the stone fragmentation can be accelerated or performed with lower energy for safer treatment. The improvement is interpreted and validated by combining high-fidelity simulations with high-speed camera images of crack formation in model stones from in vitro- experiments. [Work supported by NIH, Grant No. P01-DK043881.]
Cavitation from fundamental research to clinical applications
Authors: Hynynen Kullervo
Published: November 2021

The therapeutic use of focused ultrasound has a long history exploring both the use of inertial cavitation and thermal effects to induce tissue effects noninvasively. The thermal effects have been better understood and easier to control in clinical practice and thus they were first explored for example for cancer treatments. The utilizations of cavitation has been slower although it offers a wide spectrum of useful bio-effects. One of the first observations was that ultrasound generated gas bubbles will enhance energy absorption and can thus reduce the required energy for ablative exposures. Similar enhancement can be achieved with preformed microbubbles injected in the blood stream. These intra-vascular bubbles when excited with low pressure amplitude waves can also modulate the permeability of the blood vessels. This is most useful in organs such as brain where the endothelial cells are tightly connected forming a barrier for molecular diffusion into the tissue. The local modulation of the Blood-Brain barrier has been explored for targeted drug delivery into the brain in animal models and is now in clinical testing. In this talk the history, current status and future potential of ultrasound excited gas bodies will be discussed.
Nonlinear slow dynamic elasticity in metal systems
Authors: Yoritomo John , Dzikowicz Benjamin , Weaver Richard
Published: November 2021

Nonlinear “slow dynamic elasticity” is found to be universal amongst geological materials and other materials with complex microstructures, such as cement and cracked glass blocks. The slow dynamic behavior is characterized by a log(time) recovery, after an initial drop of stiffness, induced by strain events as small as a microstrain. Slow dynamic behavior is also reported in unconsolidated aggregates of glass beads under pressure and in single glass beads confined between glass plates, systems that are probed by diffuse ultrasound and monitored for stiffness changes using coda-wave interferometry. At present, there is no consensus as to the microphysical basis for the behavior, though hypotheses include glassy dynamics at grain-grain interfaces, microcracking, thermal activation of a distribution of atomic-scale barriers, and moisture. Here we extend the materials known to exhibit slow dynamics to include metal structures: an aluminum bead pack under pressure, and individual aluminum and steel beads confined between aluminum and steel plates, respectively. We find that the strength of the slow dynamics is largely the same as it is for glass beads, suggesting that neither cracking nor glassy micro-structures are essential.
Acoustic, thermal, and viscous modes in MEMS perforated back plates
Authors: Raspet Richard , Hickey Craig J. , Naderyan Vahid
Published: November 2021

The back plates of MEMS microphones are commonly perforated with holes with radii on the order of a few micrometers. The plates themselves are only a few micrometers thick. Acoustic propagation in small pores is usually described in terms of the fundamental acoustic mode whose solution can be derived using the Low Reduced Frequency method of Tijdeman. Higher order acoustic modes and the viscous and thermal modes are assumed to be highly attenuated and negligible in pores of longer tubes. Since the holes in MEMS are relatively short, it is possible that additional modes may be necessary to accurately calculate the acoustic losses in the back plate. To investigate this possibility, Rayleigh’s determinant is solved numerically and the behavior of the additional modes beyond the fundamental as the pore size is reduced determined. For larger tubes, all modes behave as expected, but as the tube radius is reduced, the higher order acoustic modes become non-physical, leaving only the viscous and thermal modes as possible contributors to the attenuation.
Temporal coherence of sound propagated along vertical paths through the atmosphere
Authors: Kamrath Matthew J. , Ostashev Vladimir , Wilson D. Keith , White Michael J. , Hart Carl R. , Finn Anthony
Published: November 2021

Reductions in signal coherence caused by atmospheric turbulence constrain the performance of signal processing methods. This presentation compares theoretical predictions and measurements of acoustic temporal coherence, which describes the similarity of a signal at two times. Combining sound propagation theory with turbulence models yields the theoretical coherence. To be applicable to vertical and slanted propagation, the turbulence models use height-dependent variances and length scales for the fluctuations in temperature, shear-produced velocity, and buoyancy-produced velocity. Meteorological instruments on a 135-m tower measured the required model input data. The coherence measurements used a ground-based source emitting tones between 0.6 and 3.5 kHz and nine microphones on the same tower at heights 39, 80, and 130 m. In most cases, the predicted coherences accurately approximate the measured temporal coherences. In the two early-morning trials, the measured coherence times were much larger than predicted because the atmospheric turbulence was not fully developed. Excluding these cases, the measured coherence times were in the range 0.1–100 s. For each trial, the coherence times decreased slightly more than an order of magnitude from the smallest to largest frequencies. From the shortest to the longest propagation distances, the coherence times decrease slightly less than an order of magnitude.
Effect of physical and mechanical parameters on the reflected signal from the first interface of human cancellous bone—application of Biot's theory
Authors: Sadouki Mustapha , Hamadouche Fatima Zahra
Published: November 2021

In this work, a simulated study on the effects of physical and mechanical parameters describing human cancellous bone on reflected ultrasound waves is proposed. The visco-inertial exchanges between the structure and the saturating fluid are described by the Biot theory modified by the Johnson model. A simplified expression of the reflection coefficient at the first interface is obtained in the frequency domain. This expression depends on three physical parameters which are porosity, tortuosity, and viscous characteristic length as well as the mechanical parameters; Young's modulus and Poisson's ratio. The reflected signal is calculated in the frequency domain by the product of the spectrum of the incident signal with the reflection coefficient. In the time domain, the reflected wave is obtained by taking the inverse Fourier transform of the reflected frequency signal. The effect of each parameter on the reflected signal is studied. The results obtained are discussed and compared with those given in the literature.
Children’s age matters, but not for audiovisual speech enhancement
Authors: Gijbels Liesbeth , Yeatman Jason D. , Lalonde Kaylah , Lee Adrian KC
Published: November 2021

Articulation movements help us identify speech in noisy environments. While this has been observed at almost all ages, the size of the perceived benefit and its relationship to development in children is less understood. Here, we focus on exploring audiovisual speech benefit in typically developing children (N = 160) across a wide age range (4–15 years) by measuring performance via an online audiovisual speech performance task that is low in cognitive and linguistic demands. Specifically, we investigated how audiovisual speech benefit develops over age and the impact of some potentially important intrinsic (e.g., gender, phonological skills) and extrinsic (e.g., choice of stimuli) experimental factors. Our results show an increased performance of individual modalities (audio-only, audiovisual, visual-only) as a function of age, but no difference in the size of audiovisual speech enhancement. Furthermore, older children showed a significant impact of visually distracting stimuli (e.g., mismatched video), where this had no additional impact on performance of the youngest children. No phonological or gender differences were found given the low cognitive and linguistic demands of this task.
ITD sensitivity provided to bilateral cochlear implant listeners by a mixed-rate, real-time capable processing strategy
Authors: Dennison Stephen R. , Thakkar Tanvi , Kan Alan , Azadpour Mahan , Svirsky Mario A. , Litovsky Ruth Y.
Published: November 2021

Bilateral cochlear implant (CI) listeners have limited access to interaural time differences (ITDs) at low frequencies in part because clinical processors do not coordinate the timing of stimulation across the ears. Further, clinical strategies, which are optimized for good speech reception, operate at stimulation rates that are too high [∼1000 pulses per second (pps)] to enable ITD sensitivity from the timing of pulses. Our newly developed, real-time capable sound coding strategy, delivered using a bilaterally synchronized research processor, enables binaural coordination and pulse-timed ITD encoding. We employ a “mixed-rate” stimulation approach by maintaining the capacity to provide speech or envelope ITDs on high-rate channels while simultaneously providing ITDs in the pulse timing on low-rate (100 pps) channels. We hypothesized that a mixed-rate strategy encoding both high-rate envelope ITDs and pulse ITDs would yield better ITD sensitivity than a strategy encoding pulse ITDs or high-rate envelope ITDs only. This hypothesis was tested by measuring the perceived range of lateralized auditory images in bilateral CI listeners. Preliminary results indicate listeners may have ITD sensitivity with all conditions, though the mixed-rate strategy can provide better ITD sensitivity in some listeners. This demonstrates the potential of the mixed-rate strategy for improving binaural hearing outcomes.
Speech Intelligibility evaluation in the presence of speech masker of cochlear implant in a reverberant room
Authors: Arifianto Dhany , Asyraf Muhammad A. , Amelia Ria R. , Fajriyah Latifatul
Published: November 2021

In this report, we investigated the performance of a cochlear implant (CI) in a reverberant room with the presence of a competing speech masker. We compared Short-Time Objective Intelligibility (STOI) and Perceptual Speech Quality (PESQ) to represent the objective, to percent correct word (PCW) and Mean Opinion Score (MOS) as subjective evaluations, respectively. The target and the masker speech were convoluted with 0.4- and 0.7-s reverberation time, respectively, then processed with a 14-channel vocoder. We set the target to the masker 5dB and 0 dB SNR. We simulated two well-known techniques, namely CIS and SPEAK processors. Ten normal-hearing paid subjects were participated to evaluate the performance in clean, reverberant with no masker and reverberant with masker. The results showed that performance degraded significantly as the reverberation duration increased. Furthermore, the presence of a masker to a target speech in a reverberant room worsened all the evaluated performances compared to the reverberant alone. The results suggested that further investigation is required to reduce the masker effect to improve CI intelligibility.
Simulated audiometry reveals multiple asymptotic thresholds for the same listener depending on the number of presentations at threshold
Authors: Hoover Eric C. , Palandrani Katherine N.
Published: November 2021

Changes in audiometric thresholds are used to detect auditory insult resulting from exposure to hazardous noise, blasts, and ototoxicity. Stimuli presented during audiometry reflect a stochastic process driven by listener responses, and thus a threshold can be reported after a different number of presentations, e.g., two hits and zero, one, or two misses. We interpret thresholds as equivalent despite large differences in the proportion of hits observed. To test for systematic bias in thresholds obtained after a different number of presentations, a continuous distribution of audiometric threshold as a function of stimulus level was numerically approximated for a fixed listener model tested using 2 and 5 dB ascending steps. Results were sorted by the number of presentations at threshold and summary statistics were calculated directly from the proportion of Monte Carlo simulations reporting each stimulus level as threshold. Thresholds differed systematically as a function of the number of times the threshold stimulus level was presented, consistent with a model combining the probability of meeting the stopping criteria with the asymptotic distribution of ascending trials. The implication is that recording the number of presentations at threshold on the audiogram will improve our ability to detect changes in hearing. [R01DC015051.]
Electrophysiological responses to change in spectral ripple envelope phase in normal-hearing infants
Authors: Horn David , Walter Max , Rubinstein Jay T. , Lau Bonnie K.
Published: November 2021

Spectral resolution plays an important role in understanding speech in noisy real-world listening environments. Spectral ripple discrimination is one method used to measure spectral resolution that has been shown to correlate with open-set speech understanding in adults and children who use cochlear implants. In this study, we investigate the feasibility of obtaining an electrophysiological measure of spectral ripple discrimination in very young infants. Spectral ripple stimuli were constructed from two concatenated 1-s noise carriers consisting of 2555 random phase pure tone frequency components between 100–5000 Hz, with a spectral envelope sinusoidally modulated at 1-ripple-per-ocatave with peak-to-trough depth of 20 dB. The starting phase of the first half of the stimulus varied randomly while the starting phase of the second half was “inverted”, shifted by 90-deg, relative to the first. Infants were presented with 150 repetitions of these stimuli at 80 or 65 dBA in sound field while undergoing 32-channel electroencephalography (EEG) recording. Our preliminary analyses show that an acoustic change response can be recorded in awake infants between 2 and 4 months of age in response to a spectral ripple inversion. These preliminary results suggest the potential utility of EEG in the measurement of spectral resolution in very young infants, warranting further investigation.
Comparison of speech, spatial, and qualities of hearing scale questionnaire and the abbreviated profile of hearing aid benefit in a large cohort of listeners
Authors: Srinivasan Nirmal Kumar , O'Neill Sadie
Published: November 2021

The speech, spatial, and qualities of Hearing Scale (SSQ; Gatehouse and Noble, 2004) is a 49-item questionnaire developed to assess listeners’ subjective sense of listening ability and listening experience in everyday complex situations that often involve spatial hearing. The Abbreviated Profile of Hearing Aid Benefit (APHAB; Cox and Alexander, 1995) is a 24-item self-assessment questionnaire in which listeners report the amount of trouble they have while communicating in various everyday listening situations. The APHAB assesses multiple listening environments that include ease of communication, reverberation, background noise, and aversiveness of sounds. Even though both the questionnaires measure the self-reported hearing ability/disability, there are very few studies in the literature that compares the outcome of these two questionnaires on same group of listeners. Both the questionnaires were administered to198 listeners (younger: n = 107, mean age = 22.8 years, range: 19–25 years; older: n = 91; mean age = 53.5 years, range: 40–70 years) through Qualtrics. The differences and relationships between the two groups for both the questionnaires will be discussed. These data are intended to aid in interpreting the SSQ and APHAB results in typical audiological clinics.
Central gain in aging, tinnitus, and temporary hearing loss
Authors: Dougherty Kelsey , Hustedt-Mai Alexandra , Hagedorn Anna , Bharadwaj Hari
Published: November 2021

The nervous system adapts in many ways to changes in the statistics of the inputs it receives. An example of such plasticity observed in animal models is that central auditory neurons tend to retain their driven firing rate outputs despite reductions in cochlear input due to hearing loss or deafferentation. The perceptual consequences of such “central gain” are unknown; pathological versions of such gain are often hypothesized to underlie tinnitus and hyperacusis. To investigate central gain in humans, we designed an electroencephalogram (EEG)-based paradigm that concurrently elicits robust separable responses from different levels of the auditory pathway. Using this measure, we find that cortical responses are relatively invariant despite a large monotonic decrease in auditory nerve responses with age, and that this central gain is also associated with perceptual deficits in co-modulation processing. We then applied the same measures to a cohort of individuals with persistent tinnitus and to a third cohort where a week-long monaural conductive hearing loss was induced using silicone earplugs. Overall, our results suggest that central gain is ubiquitous in response to reduced peripheral input and may affect auditory scene analysis, but does not in itself account for tinnitus perception.
The relationship between speech perception and production in 4-year-old children with hearing loss
Authors: Oster Monika Maria
Published: November 2021

The ability to produce speech is linked to accurately perceiving speech, which is challenging for children with hearing loss (HL). Additionally, the interactions through which children acquire speech frequently occur in difficult listening environments. This preliminary study aims to describe the relationship between perception of quiet speech/speech in noise and speech production skills in 4-year-old children with HL. The analysis used clinical assessment data. Only children with mild to profound bilateral HL using hearing aids (HAs) or cochlear implants (CIs) were included. Articulation was assessed through the GFTA (HA = 39, CIs = 43). Speech perception was assessed in 23 children through the NU-CHIPS, WIPI or PBK-50 in two conditions: 35dB in quiet and 50dB in 45dB multitalker babble. The results showed that speech production skills were similar for children with HAs (mean SS = 83.77) and CIs (mean SS = 79.88) and were not correlated with speech perception. However, results may have been influenced by the verbal responses required for the PBK-50. After its exclusion, results showed a moderate positive correlation between speech production and the perception of quiet speech (r = 0.5) and speech in noise (r = 0.66).