bluuebunny/crossref_metadata_2025 huggingface dataset:
Life cycles of free reed instruments: The accordion-concertina family and the reed organ-harmonium family as case studies
Authors: Cottingham James P.
Published: May 2022

In 1800, the free reed instruments of European origin did not exist. Beginning in the 1820s, there was very rapid invention and innovation in the development and production of instruments like the reed organ and accordion so that within a few decades these instruments had reached something approaching their final form. By 1900 instruments with hand-driven bellows (accordions and concertinas) and instruments with foot-driven air supplies (reed organs and harmoniums) of a wide variety of types were being manufactured and played worldwide in large numbers. From around 1900 through the 1920s, there was a sharp drop in the number of new reed organs and harmoniums manufactured and sold. This number decreased to near zero by mid-century and has remained there. Meanwhile, the manufacture of the “squeeze box” instruments has remained robust to the present day. Factors involved in the discrepancy between these two families of instruments of almost identical acoustical design will be discussed. These include changes in musical styles and taste, socio-economic factors, and competition from other musical instruments.
Spatial coherence of vertical atmospheric sound propagation
Authors: Kamrath Matthew J. , Ostashev Vladimir , Wilson D. Keith , White Michael J. , Hart Carl R. , Finn Anthony
Published: May 2022

Atmospheric turbulence causes the amplitude and phase of sound waves to fluctuate, which reduces the coherence of acoustic signals. Spatial coherence describes the similarity of two signals at different points in space, and a better understanding of acoustic coherence could lead to improved target detection, tracking, and identification. This presentation compares theoretical predictions and measurements of the acoustic spatial coherence. The theoretical coherence is derived by combining sound propagation theory with turbulence models that include the effects of atmospheric shear and buoyancy instabilities. 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. Instrumentation on a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO) provided the required model input data. The coherence measurements used a ground-based source and nine microphones attached to the same meteorological tower. Overall, the theoretical model accurately approximated the measured spatial coherences, especially when the atmospheric turbulence was fully developed (e.g., in the afternoon on sunny days). The largest disagreement occurred for measurements taken at dawn. For a source frequency of 3.4 kHz and microphones that are 130 m high and 1.5 m apart, the measured coherence was 0.3–0.6 for sunny conditions and 0.8–0.9 for cloudy conditions.
Development of software for performing acoustic time reversal with multiple inputs and outputs
Authors: Kingsley Adam D. , Anderson Brian E.
Published: May 2022

At Brigham Young University, acoustic time reversal experiments are conducted in solids and fluid media. The experimental setup involves synchronized generation and acquisition hardware. The synchronized hardware allows for multi-channel generation, and in some cases, multi-channel acquisition of time reversal focusing. A LabVIEW application has been compiled to increase ease of use and repeatability for the students conducting experiments. Forward and backward steps of time reversal are conducted through this simple user interface. The software is also able to control a 2D positioning system that allows for the measurement of the spatial extent of a time reversal focus. Modifications to traditional time reversal processing, such as inverse filtering and one-bit processing, may be easily implemented in the software. This presentation describes the hardware and software that help to facilitate time reversal research. Ideas from this presentation may help others develop time reversal data acquisition systems.
Imaging watermelons
Authors: Zartman David J.
Published: May 2022

Watermelons are enjoyed by many all over the world. The challenge to find the perfect ripeness desired is one most easily answered using acoustic imaging, though most would commonly refer to this as a thump test. Basically, impact from a flicked finger does not do damage to the fruit, but can create an impulse in the watermelon, generating a response within the fruit that can be both felt and heard. How can this be interpreted for best results though? Watermelons start out firm and fibrous, and as they ripen fluid becomes more prevalent and sweeter, until there is more fluid than fiber and the fruit is deemed old and squishy. Thus, the two extremes are pure fibrous solid and a bag of fluid. The actual quest is in-between the two, finding the optimal balance. When there is both fiber and fluid in the fruit, it is very resonant. The amount of resonance directly corresponds to the balance between fiber and fluid. Some prefer more fiber for more crunch, and some prefer more fluid for a sweeter juicier product. Knowledge of how watermelons ripen and appropriate acoustic imaging techniques can allow the common grocery shopper to acquire their optimal product.
Comparison of waveform estimated using inverse filtering with direct measurement of the volume flow at the glottal exit
Authors: Michaud Jacob J. , Oren Liran , Farbos de Luzan Charles , Gutmark Ephraim , Khosla Sid M.
Published: May 2022

Inverse filtering is a signal processing technique used to estimate the glottal waveform from the speech signal. Although this technique is regularly used in research studies, it has never been formally validated because of the difficulties in obtaining direct measurements of the glottal airflow. The objective of this study is a first step towards validating this technique by comparing its estimated glottal waveform with flow measurements taken simultaneously at the glottal exit. The setup is based on synthetic vocal folds connected to a vocal tract model. Direct measurements of the volume flow at the glottal exit are taken using time-resolved tomographic particle image velocimetry. A circumferentially vented pneumotachograph (i.e., Rothenberg) mask is connected to the vocal tract and used with the Glottal Enterprise system to calculate the glottal waveform using inverse filtering. Effect of varying subglottal pressures and effect of near-field (i.e., the minimal gap between the false vocal folds) and far-field (i.e., oral opening) constrictions were also investigated. Results show that overall using inverse filtering gives a good approximation of the glottal flow waveform, but its accuracy can change depending on the constrictions in the vocal tract. The clinical implication of these findings will be further discussed.
The Arctic underwater soundscape today and as projected for 2030
Authors: Heaney Kevin D. , Verlinden Christopher , Seger Kerri D. , Brandon Jennifer , Hatch Leila , Schönau Martha , Heaney Andrew
Published: May 2022

Canada, the United States, and the World Wildlife Fund are co-sponsoring ongoing work in the Arctic Council’s Protection for the Marine Environment Working Group to evaluate shipping noise in the Arctic region. Applied Ocean Sciences has used ship tracking and sea ice data to model the region’s underwater soundscape to improve understanding of radiated noise generated by shipping throughout the PanArctic. Current (2019) models have been compared with ambient noise measurements collected during time periods when vessel sounds were identifiably present and when biological sounds were not. Projections of ice cover and shipping routes along and between the northern borders of Arctic countries were used to forecast potential future (2030) Arctic soundscapes. Focused interpretation of these model results within sub-regions, time periods, and frequencies important to marine fauna and in turn to indigenous peoples will be provided to PAME and other fora seeking to guide the development of shipping practices and mitigation strategies. The final results will be incorporated as a PAME/Arctic Council product. This presentation will focus on the acoustic modeling work under projected sea ice conditions, maps of “excess noise” induced by ships in 2019 and 2030, and risk assessment for a few endemic marine mammal species.
Architecture and acoustics in an era of experimentation
Authors: Gayley Clifford
Published: May 2022

Architecture and acoustics are inextricably intertwined using the same tools (volume, shape, surface) to create places for the exchange of ideas transmitted through sound, movement, and words. While true for well-established building types such as concert halls, theaters, and opera houses, this intertwining is key for new, emerging building types that respond to changing client demands across higher education, cultural institutions, and the public sector. Several case studies (The Pop-Up, The Cauldron, The Mash-Up, The Inversion, and The Immersion) will explore: (1) How learning institutions are repositioning the arts with new types of facilities that encourage innovation, creativity, and transdisciplinary collaboration, within the Arts and across all disciplines; (2) How learning institutions are experimenting with spaces for incubation, rehearsal, and performance, blurring the line between front of house and back of house; (3) How learning institutions are reconceiving convening/performing with audience members as active participants; (4) How performance venues can be welcoming for all members of the community and deepen engagement with the world around them (whether urban or sylvan) while maintaining acoustic excellence; (5) How large and often underutilized lobby spaces can be reimagined as pop-up venues for impromptu sonic events; (6) How acoustics can enable programmatic mash-ups such as a public radio broadcast studio and café at a library front door, opening new possibilities for building inclusive communities.
Design thinking of the Multiform Theatre: A case study
Authors: Crossfield Scott A.
Published: May 2022

Multiform Theatres are perhaps the most complex theatres to design. They must support the artistic aspirations of musicians, actors, dancers, directors, designers, and visual and aural artists in one highly flexible, transformable space. A true Multiform Theatre seamlessly supports the creation of art through automated architecture altering the Artist/Audience relationship and adapting to the artist’s spatial needs, while providing adaptable technical and acoustic opportunities that inspire new artistic forms. When done right, the architecture itself becomes part of the artistic process. How does one space change from a 625-seat Concert Hall to a 350-seat Recital Hall to a 250-seat Proscenium Theatre to a laboratory for Immersive Environments, Research and Experimentation? Join Scott Crossfield, ASTC from Theatre Projects as he guides you through the design thinking behind the new Multiform Theatre at Brown University—a radical, one-of-a-kind theatre machine designed to inspire innovative new art making, enable unprecedented artistic collaboration and serve as a hub for performance at the Brown University.
Audio/video consultants as interpreters and advocates
Authors: Perez Tim
Published: May 2022

As technical designers in the architecture world, AV Consultants help architects realize their vision while preserving an appropriate and useful AV system for the people who will occupy the space for years afterward. By involving users in the design process and communicating with user-focused language, we can identify functional expectations and be free to engineer a coordinated system solution with the design team. Recognizing that many of our clients only see a big building project once or twice in a lifetime, an effective design process involves seeking input from a broad range of users, setting clear expectations, presenting design progress in a meaningful and context-based manner, and creating a sense of ownership for decisions made along the way. Users may start with lofty goals and idealistic aspirations for a project, but one that is designed and managed responsively can still be successful through expectation-setting and opening the process to those who will have to live with the results.
Acoustical criteria and design approaches for music education and rehearsal spaces
Authors: Siebein Gary W. , Roa Marylin , Vetterick Matthew , Miller Jennifer
Published: May 2022

Case studies of three music education spaces will present acoustical measurement data with architectural features of the rooms compared to criteria from Sabine (1964), Pirn (1978), Gade (1988), Wenger (2008), and Tsaih (2011) among others to assess the sound qualities of the spaces. Among other qualities, reverberation time, room volume, hearing each other, and speech intelligibility are evaluated. Data are also compered to the Norwegian Standard NS 8178-2014. The case studies show how these criteria can be achieved given very different architectural systems employed in the rooms and describe the limits of where the qualities cannot be achieved due to the limits of program, budget, site, or space. Efforts are made to make each surface in the rooms acoustically productive in an optimized design to the extent practicable.
Viscoelasticity inversion for arterial shear wave elastography
Authors: Roy Tuhin , Guddati Murthy
Published: May 2022

Arterial stiffness, an important biomarker of many cardiovascular diseases, is strongly influenced by the wall modulus. In shear wave elastography, the arterial wall is excited by acoustic radiation force, and the resulting wave propagation characteristics are used to infer arterial stiffness. In earlier ASA meeting, we presented a forward model that returns arterial wall motion for a given geometry, material properties of the waveguide, and input acoustic radiation force. In this work, we propose an inversion approach developed on this forward model to estimate arterial viscoelasticity, which is also considered an important biomarker. Recently, the phase-velocity dispersion is utilized to estimate the arterial wall elastic modulus. However, this approach fails to estimate the viscoelastic modulus since the dispersion curve is not strongly influenced by the arterial wall viscoelasticity. Conversely, the spatiotemporal representation of the wall velocity is sensitive to both moduli. Therefore, in the inverse model, we minimize the mismatch between the measured and simulated particle velocities to invert for the parameters of viscoelasticity, e.g., modulus and damping coefficient for the Voigt model, modulus, and exponent for the Spring-pot model. This talk would contain the details of the underlying formulations and numerical examples illustrating the effectiveness of the proposed approach.
Full-waveform shear wave elastography for imaging tumors
Authors: Elmeliegy Abdelrahman M. , Guddati Murthy
Published: May 2022

Shear wave elastography (SWE) is a method of reconstructing the stiffness of soft biological tissues by matching the observed and the simulated wavefields using an inverse optimization scheme. SWE reconstruction algorithms can be classified into two main categories, local and global methods. Global methods consider more complete physics of the waves, i.e., refraction and scattering, and, thus, have the potential to better characterize the heterogeneity of the domain. These approaches require full-waveform inversion (FWI), which is computationally expensive. More importantly, due to highly nonlinear nature, FWI has the limitation of converging to local minima, leading to erroneous reconstruction. In this work, we address this issue and propose a cost functional that not only reduces the nonlinearity of the FWI but also results in a reconstruction algorithm that is independent of push amplitudes, less sensitive to the initial guess, and has a better convergence behavior compared to the classical least-squares cost functional. In addition, we propose to utilize only a fraction of the measurements with the eventual goal of 3D reconstruction of tumors using limited ultrasound measurements. In this talk, we will present the details of the underlying formulation and examples showing the effectiveness of the proposed method.
Motion-corrected echo decorrelation imaging for monitoring exvivo cardiac ablation
Authors: Saremi Bahar , Grimm Peter D. , Ghahramani Z. Elmira , Schoenleb Nicholas S. , DeMazumder Deeptankar , Mast T. Douglas
Published: May 2022

Radiofrequency ablation for treatment of cardiac arrhythmia would benefit from real-time monitoring of ablation progress. Echo decorrelation imaging has been shown to predict local ablation but is susceptible to artifacts caused by heart motion. Here, a method for motion-corrected echo decorrelation imaging is tested in ex vivo ablation of bovine cardiac muscle with controlled motion. Experiments employed a Stockert 70 generator and a 4-mm Celsius catheter (Biosense Webster) with the ablation duration of 3min at the target ablation temperature of 90 °C, resulting in thermal lesions of diameter about 1 cm. Cyclical motion was induced by a stepping motor system (Velmex) with velocities of 0–10 mm/s in the travel range of 1.5 cm. Pulse-echo ultrasound images were acquired by an Acuson SC2000 scanner with a Z6Ms transesophageal matrix array (Siemens). Throughout ablation at intervals of 5–6 s, sequentially paired bi-plane images were acquired as complex (IQ) beamformed echoes with an interframe time of 9–13 ms. Regions of interest (ROIs), one including the catheter location and one outside the ablation zone, were tracked using detection of the myocardial wall boundary and spatial cross-correlation. Echo decorrelation within the ablation ROI was then mapped and compensated to remove motion-induced decorrelation measured in the reference ROI. Receiver operating characteristic curves characterize accuracy for predictions of local myocardial ablation by motion-compensated echo decorrelation imaging as a function of the induced motion amplitude.
The evolution of microwave-induced thermoacoustic signal characteristics generated during pulsed microwave ablation
Authors: Evans Audrey L. , Hagness Susan C. , Ma Chu
Published: May 2022

Microwave-induced thermoacoustic (TA) signals are of emerging interest for monitoring microwave ablation (MWA) in real-time. TA signals can be generated using an interstitial ablation antenna with a pulsed microwave energy source. When a microsecond microwave pulse is absorbed by tissue, the tissue undergoes a small-scale temperature rise, inducing a thermoelastic expansion that leads to acoustic generation. TA signal characteristics are linked to the dielectric, thermal, and acoustic properties of the local ablation environment. These relevant properties evolve significantly during the ablation process. We conducted a simulation-based study to examine the evolution of microwave-induced TA signal characteristics generated during pulsed microwave ablation. We experimentally validated our multi-physics simulation model for a spatially uniform temperature profile. Then, using the validated simulation model, we investigated TA signals generated in tissue exhibiting spatially nonuniform temperature profiles that arise during MWA. We find that TA signal characteristics are highly influenced by the local environment temperature within the region of initial TA generation and, thus, contain rich information to be exploited for real-time ablation monitoring.
Investigation of a noninvasive method for monitoring intracranial pressure using sheep skulls
Authors: Cameron Nicholas , Piacsek Andrew A.
Published: May 2022

It has been previously demonstrated that resonance frequencies of fluid-filled shells of simple geometry are shifted in proportion to fluid pressure [J.Acoust. Soc. Am. 131, EL506 (2012)]. We investigate the applicability of this approach for measuring changes of intracranial pressure in ovine skulls. A catheter inserted through the foramen magnum of a complete sheep’s head enables the control of hydrostatic pressure, which is measured independently using a pressure transducer inserted into the parenchyma through a drilled hole in the skull. The vibrational response is measured using a small modal impact hammer to gently tap the skull with small accelerometers mounted at different locations on skull. Acceleration normalized by impact force is computed in the frequency domain, averaged over multiple taps. Significant peaks in the response spectrum are identified and associated with vibrational modes observed using a laser Doppler vibrometer. The consistency with which peaks shift in frequency in proportion to ICP is reported. The effect of tap location and accelerometer placement is also explored.
Pulse wave propagation through a stenotic artery with plaque constituents of different stiffnesses: In vitro-experiment and fluid–structure interaction simulation
Authors: Mobadersany Nima , Meshram Nirvedh H. , Konofagou Elisa
Published: May 2022

Vulnerable (typically, softer) carotid plaques may rupture leading to blockages downstream in the brain with high potential for ischemic stroke. Pulse Wave Imaging (PWI) developed by our group is an ultrasound-based technique for pulse wave visualization and pulse wave velocity (PWV) mapping. In this study, the accuracy of PWV estimation in stenotic vessels was assessed in simulation and phantom studies. Fluid–structure interaction simulations were performed in a stenotic (50%) vessel. Experimental stenotic (50%) polyvinyl alcohol (PVA) phantoms (2 mm thickness, 8 mm lumen diameter, and 165 mm length) with soft/medium/hard plaque constituents of different stiffness (E0 = 12 kPa, 30 kPa, 94 kPa) were constructed matching the simulation geometry and parameters. Pulse waves were generated by a computer-controlled pump using a physiologic flow waveform. The RF frames were acquired by a Verasonics Vantage 256 system using a 5 MHz (L7-4) linear array. The acquired RF frames were beamformed using a delay and sum algorithm, and a GPU-based, 1-D cross correlation method was used to estimate the wall velocities. The acceleration peak of the pulse wave was tracked to estimate PWV. PWVs of 2.6 ms−1, 3.4 ms−1, and 4.5 ms−1 were, respectively, measured for the soft, medium, and stiff plaque material in experimental phantoms. The PWV of 2.7 m/s was confirmed for the medium plaque in simulation. This fundamental study demonstrated, thus, a good accuracy by PWI in the estimation of plaque PWV and its underlying stiffness for future stroke risk assessment.
Time-domain formulation for coherent plane wave compounding in horizontally layered media
Authors: Cormack John M. , Simon Marc A. , Kim Kang
Published: May 2022

The locations of origin of ultrasonic echoes from soft tissue in conventional ultrasound beamforming are based on measured time of flight. For simplicity it is usually assumed that the region of interest is homogeneous with a constant sound speed, but in many in vivo and benchtop applications the imaging region is composed of horizontal layers, each with a distinct sound speed. In addition to time-of-flight complications, sound speed differences between the layers result in refraction through the interface of both the transmitted pulse and those reflected from the tissue, further influencing the fidelity of beamforming for target localization or other quantitative ultrasound metrics. A formulation is presented for delay-and-sum coherent Plane Wave Compounding (PWC) that accounts for variation in sound speed and refraction of ultrasound pulses in a region with two horizontal layers. The algorithm is formulated completely in the time domain, enabling simple implementation or extension of existing homogeneous PWC algorithms. Simulated and experimental images are investigated for a typical two-layer benchtop configuration, where the sound speeds in the upper and lower layers are relatively slow (water or gel) and fast (muscle), respectively. Extension of the formulation to a medium with N distinct layers is discussed.
Avoiding common pitfalls in health effects of noise research: Instructive observations from updating the International Bibliography on Noise
Authors: Swift S. Hales
Published: May 2022

During a recent effort to update the International Bibliography on Noise (IBON), the present author reviewed papers involving human annoyance evoked by community noise as a subject matter expert. As part of that effort, a number of papers on physiological health effects and their relationship to annoyance were evaluated. Many of the research products reviewed relied on self-reported measures of noise or used noise annoyance as a proxy for noise exposure instead of using either predicted or measured exposure values. This approach introduces substantial uncertainty into the interpretation of the results. Indeed, a smaller set of studies that included both physical and perceptual measures of exposure shows substantial differences between the results obtained via these contrasted approaches to exposure assessment. Some of the multiple directions of causality involved in the relationship between noise sensitivity, noise annoyance, psychological traits, and health effects are discussed in an effort to provide a cautionary resource for future efforts to study these relationships in ways that avoid certain well-traveled pitfalls. [Funded by the Air Force Civil Engineer Center under an interagency agreement between the Air Force Civil Engineer Center and the U.S. Department of Energy/Argonne National Laboratory, No. SAND2022-0676 A.]
Peak sound pressure level decay from large C-4 detonations: Establishing a 140 dB threshold
Authors: Sorrell Avery K. , Gee Kent L. , Rasband Reese D. , Pemberton Steven , Laintz Kenneth E.
Published: May 2022

Far-field acoustical characterization of blast wave propagation from explosives is often carried out using relatively small shot sizes (less than 1 kg). This paper describes a series of eleven C-4 detonations, with shot sizes varying from 13.6 kg to 54.4 kg (30 to 120 lbs) that were recently measured at the Big Explosives Experimental Facility (BEEF) at the Nevada National Security Site. Pressure waveform data were recorded at up to nine different stations, ranging from 23 m to 2.7 km from the blast origin, with some angular variation. As part of examining blast overpressure decay with distance and comparing with literature, the data were analyzed from the context of human safety regulations. To provide improved guidance for BEEF personnel working distances, an empirical model equation was developed for the distance, as a function of shot size, at which the peak pressure level drops below 140 dB. A preliminary investigation into peak level variability due to wind was also conducted. [Work supported by Los Alamos National Laboratory.]
Theory of parametric receiving arrays processing utilizing sum and difference frequencies
Authors: Bender Christopher M. , Lani Shane W.
Published: May 2022

The majority of highly directive receive arrays obtains their directivity from an often fully populated (lambda/2 spacing) array in one or more dimensions. Digital beamforming allows for steering of these densely populated arrays in multiple directions; however, if there is only one primary direction of interest, a similar highly directive receiver can be generated with just a few elements. Parametric receivers, such as parametric sources, can obtain enhanced directivity via a “virtual aperture” or a region in the medium where nonlinear mixing of a high intensity pump wave and a signal wave interact. For a parametric receiver, the pump element(s) with a frequency, F, and receiver element(s) are separated by a distance, L, and the signals of interest are the sum and difference frequency (F + /− f) between the pump frequency and an incoming signal frequency, f. The directivity of these parametric receivers are comparable to the end fire response of a line array of similar length, L. This paper will review the highlights of parametric receivers as well as detail the analysis to extend this phenomenon to include the sum and difference frequencies for single element pairing and arrays of pumps and receivers.
Modeling receiver characteristics of parametric receiving arrays
Authors: Lani Shane W. , Bender Christopher M. , Flynn Tyler J.
Published: May 2022

Parametric receivers, such as parametric sources, can obtain enhanced directivity via nonlinear mixing of a high intensity pump wave and an incoming signal wave. Receiver properties, such as directivity and sensitivity of a parametric receiving arrays, can be derived from the physical characteristics such as the separation distance of the pump and receive elements, the pump wave frequency, and the incoming signal wave frequency. The overall receiver characteristics are also dependent on the medium properties such as the acoustic nonlinear parameter and absorption, as the medium is key to mixing of the waves. The parametric receiver’s noise floor is a function the noise around the signal band and the noise native at the resultant sum and difference frequencies. This paper will present the analysis of noise for parametric receivers as well as modeling results leveraging a k-space pseudospectral method solver of the Westervelt equation. Comparisons of the directivity of the parametric receivers will be made between the modeling to the analytic theory.
COMSOL modeling of time reversal focusing in a periodic network of Helmholtz resonators
Authors: Kingsley Adam D. , Anderson Brian E.
Published: May 2022

This presentation will outline the physical and practical considerations for conducting a COMSOL simulation of time reversal focusing in air. Attempts to obtain sub-diffraction-limited time reversal focusing, along with physical and practical consideration, will be presented. Physical considerations include end-corrections, resonator shape and placement, computational domain and anechoic terminations. Practical considerations include mesh size and temporal length. While conducting a time domain study in COMSOL, mesh size is related to the highest frequency and the simulation length is related to the lowest frequency. To maximize computational resources, the simulation uses a restricted bandwidth. Extending the bandwidth is accomplished by combining multiple simulations. Comparison to previous super resolution studies as well as the authors’ equivalent circuit model will also be discussed.
Complex frequency sink
Authors: Rasmussen Curtis , Rosa Matheus , Lewton Jacob , Ruzzene Massimo
Published: May 2022

As the time-reversed analog of the source, the sink is an abstraction of a device that can absorb incident symmetrical waves at a point. Such a device is useful for its ability to create an arbitrarily small focusing spot, surpassing the conventional diffraction limit. Sinks have been created using impedance matching and active cancellation; however, these techniques require the introduction of tailored loss or gain into the system. Here, we demonstrate a new method for creating a sink that requires no loss or gain but instead relies on complex frequency excitations, harmonic excitations that exponentially grow or decay in time. Recent work has shown how complex frequency excitations in Hermitian systems enable phenomena such as PT symmetry and perfect absorption that are typically only associated with non-Hermitian systems. We will discuss the theory of the complex frequency sink and analyze the case of a sink in a thin elastic plate. We will present experimental results where the scattering of a symmetric scatterer is minimized by complex frequency waves launched by piezoelectric patches. Laser-doppler vibrometer measurements of the plate shows the resonator’s curious behavior as a loss and gain free sink.
Impedance tube measurements of 3D printed porous materials
Authors: Fitzpatrick Noah , Frederickson Carl
Published: May 2022

The acoustics of porous media affects what materials are good for sound control in enclosed environments. The theories used in this area model porous materials as having continuous unconnected pores. The important physical factors in these theories are the porosity (ratio of pore volume to sample volume), tortuosity (ratio of pore length to sample depth), and flow resistivity (resistance to air flow through the sample). The models allow for calculation of acoustic properties but are not truly representative of most porous media. With the advent of 3D printing, it is possible to design and print 3D media with specific porosity and tortuosity characteristics. These materials can be used in an impedance tube to test the validity of the models being used. Porous plugs will be designed and 3D printed using stereolithography. The plugs’ acoustic properties will be measured in an impedance tube. The results of this project will provide data that can be used to refine the acoustic models of porous media.
Design and manufacture of synthetic pinnæ for studying head-related transfer functions
Authors: Sumner Eric M. , Riedel Morris , Unnþórsson Rúnar
Published: May 2022

The study of head-related transfer functions (HRTFs) is hampered by an inability to isolate the effects of individual anthropometric properties in an experimental setting. The authors propose to address this issue by studying the HRTFs of synthetic pinnæ which are designed to specification. The design, manufacture, and measurement of these synthetic pinnæ are detailed: A mold for each pinna is printed with a finite-deposition 3D printer and then cast in silicone with appropriate acoustic properties. These castings are then installed on a KEMAR mannequin whose HRTF is measured in an anechoic chamber. Additionally, comparative results are presented between commercially produced pinnæ inserts and copies produced via the proposed method.
Multilevel probit regression for 3-alternative forced choice audibility testing
Authors: Boucher Matthew , Christian Andrew , Rafaelof Menachem , Shepherd Kevin , Rizzi Stephen A. , Stephenson James
Published: May 2022

A recent psychoacoustic test at NASA Langley generated a dataset of 3-alternative forced-choice responses for 40 subjects that measured the audibility of a tone complex in a shaped broadband masker. The task was completed by four subjects at a time in a small theatre-like environment using predetermined stimuli levels. These data were subject to 4 forms of probit regression: a “complete pooling” analysis in which all data from the test was fit with one curve, two forms of “no pooling” analyses in which subjects’ data were treated individually (using both packaged and custom software), and a “partial pooling” analysis in which multilevel-regression software fit both individual curves as well as population-level parameters at the same time. The results of the analyses are compared in terms of both individual- and population-level parameters. Partial pooling appears to give the most consistent results at both levels, as well provide the most robustness among the packaged approaches (albeit with added complexity over single-level regression). These results mirror those contained in a recent NASA technical memorandum entitled “Comparisons of Analysis Methods Applied to Alternative Forced Choice Audibility Data.”
Portable automated rapid testing in Spanish: Validation and norms of central hearing processes on a Mexican population
Authors: Lelo de Larrea-Mancera E. S. , Solís-Vivanco Rodolfo , Sánchez Jiménez Yolanda , Coco Laura , Gallun Frederick J. , Seitz Aaron
Published: May 2022

Portable automated rapid testing of central auditory processing measures implemented in the app PART (https://braingamecenter.ucr.edu/games/p-a-r-t/) were adapted for Spanish-speaking populations. This adaptation included the generation of a corpus equivalent to the CRM to test a speech-on-speech masking task, in addition to frequency modulation tasks, temporal gap, temporal, spectral and spectro-temporal modulations, and pure tone detection in noise. This battery of tests was selected for its potential clinical utility and its previous validation across several settings including remote testing with participant-owned headphones, tablets or smartphones. Here, we tested 96 young adults in Mexico City (ages 18–45) with normal hearing. As expected, distributions of scores were similar to previously reported norms for the English-language version of the battery in English-speaking populations. Scores for the newly developed Spanish-language speech-on-speech masking tests were also similar to data previously reported in English-speaking populations. Furthermore, there was no significant effects of age or subjective hearing handicap (HHIA) in any of the tests. This study can be now used as a normative dataset, and the adapted battery can be used as an accsessible tool (available freely online) for valid and reliable testing of central auditory processing measures in Spanish-language populations.
Extensions of a neural-fluctuation perspective on simultaneous notched-noise masking
Authors: Maxwell Braden , Abumuaileq Mohammed , Carney Laurel H.
Published: May 2022

A previous paper [Maxwell et al., J. Acoust. Soc. Am. 3523, 3537 (2020)] suggested that listeners may identify the target interval in a simultaneous notched-noise task using neural fluctuations, which change with the addition of a tone to the masker. Neural fluctuations are changes in the instantaneous firing rate of auditory-nerve fibers, generally at a longer (slower) time scale than temporal fine structure, that are shaped by peripheral nonlinearities. Differences in neural-fluctuation amplitudes across the peripheral tonotopic axis are proposed to lead to differences in rates across the population of auditory midbrain neurons, due to the sensitivity of these neurons to amplitude modulation. Here, using similar methods to Maxwell et al. (2020) and stimuli matching those of Baker and Rosen (J.Ascoust. Soc. Am. 454, 462 (2006)], we extend previous work by demonstrating that neural fluctuations may account for additional features of simultaneous notched-noise masking results. These features include (1) increase in filter bandwidth at higher stimulus frequencies, (2) higher bandwidth with increasing masker level, and (3) filter asymmetry. These results, in conjunction with the previous conclusion that auditory-nerve excitation patterns cannot explain notched-noise thresholds in all cases, support the interpretation that psychophysical auditory filters may be based on the output of the subcortical auditory system. [Work supported by NIDCD-R01-010813.]
Psychoacoustic thresholds measured using the Portable Automated Rapid Testing (PART) iPad application in a large cohort of older listeners
Authors: Srinivasan Nirmal Kumar , Kim Janet , Coleman Kayla , Brown Kelly , Ananthakrishnan Saradha , Hoover Eric C. , Gallun Frederick J.
Published: May 2022

Traditional methods used to assess the auditory processing capabilities of individuals have limited clinical applications as they are time consuming and require specialized hardware. Portable Automated Rapid Testing (PART) is a free application that allows various clinical assessments to be conducted in an automated and rapid fashion using commercially available consumer headphones. Use of this platform in an uncontrolled listening environment has been validated in young listeners with normal hearing, yielding thresholds similar to those reported in laboratory studies. Here, we report auditory processing capabilities measured using PART in a large cohort of older listeners with varying hearing capabilities. Psychoacoustic thresholds for gap detection, spectrotemporal modulation detection, dichotic and diotic frequency modulation detection, and spatial release from masking were obtained from 70 older listeners (age range: 40—75 years; 3-frequency PTA: 8.33—48.33 dB HL). Initial analyses revealed that the thresholds obtained using PART were similar to thresholds obtained in a laboratory environment. Results demonstrate that PART can be used with older listeners with minimal instruction and validate the use of a consumer platform and rapid techniques for the assessment of auditory processing capabilities in older adults with a range of hearing ability.
Effect of stimulus complexity on the phonemic restoration effect
Authors: Srinivasan Nirmal Kumar , O'Neill Sadie , Patro Chhayakanta
Published: May 2022

The phonemic restoration effect is the increase in speech intelligibility when the silent portions of the interrupted speech were replaced by a noisethat is louder than the speech signal itself. Previous research has demonstrated that the phonemic restoration effect is maximum when the interruption rate is between 1.5 and 3 Hz with a 50% duty cycle. Here we present phonemic restoration results obtained using five different speech corpora varying in stimulus complexity (least complex – most complex): (1) Callsign Acquisition Test (CAT); (2) Co-ordinate Response Measure (CRM); (3) Boston University Corpus (BUC); (4) IEEE sentences; and (5) R-PRESTO obtained from a group of young normal-hearing, listeners. Interruption rates of 2 Hz and 3 Hz were used and speech shaped noise was used to fill the silent interruptions. Initial analyses of the data revealed that the phonemic restoration effect was absent for the least complex stimuli (CAT) because of ceiling effects and the amount of restoration increased as the complexity of the stimulus increased. The effect of interruption rate and signal-to-noise ratio between the speech and noise on the phonemic restoration effect will also be discussed.
Measuring harmonic benefit in musicians and non-musicians in several tasks
Authors: Guest Daniel R. , Rajappa Neha , Oxenham Andrew J.
Published: May 2022

Prior work has demonstrated that harmonic tones are easier to detect in noise and yield better F0 discrimination in noise than inharmonic tones. These effects, referred to as harmonic benefit, appear to be approximately the same size in musicians and non-musicians, despite musicians’ overall better pitch discrimination. The present study aimed to replicate these findings and extend them to include measurements of harmonic benefit in other tasks. Non-musicians and musicians were compared in four tasks: detection in noise, F0 discrimination, FM detection, and AM detection. The stimuli in each task were either harmonic or inharmonic complex tones and were presented in threshold-equalizing noise at a range of signal-to-noise ratios. We found that harmonic benefit for F0 discrimination was large and remained large even after accounting for differences in the detectability of harmonic and inahrmonic tones. In contrast, harmonic benefit was small for FM and AM detection and could mostly be accounted for by differences in detectability. In contrast to prior studies, we found that musicians showed a larger harmonic benefit than non-musicians. These results provide insight into how musical training may specialize the auditory system for processing of harmonicity and pitch. [Work supported by NIH grants F31 DC019247 and R01 DC005216.]
Enhancing wear prediction with spectral analysis of noise and the dynamic response of the structure
Authors: Lawal Iyabo G. , Brake Matthew R. , Haberman Michael R.
Published: May 2022

High frequency noise has been observed during reciprocating sliding of metal-metal in dry contact. In tribology, the study of friction and wear, this noise was historically associated with “brake squeal;” however, it has also been found to occur within structures and systems that experience high frequency, reciprocating contact of metal constituents; typically found in the connecting locations such as the joints of a variety of jointed structures ranging from automobiles, airplanes, and HVAC systems. This type of tribological behavior and fretting fatigue has been replicated in tribology experiments where researchers found increased noise followed with the increase in sliding velocity and lowered relative humidity [1]. It was also found in these experiments, that noise is only produced during the tension phase of the fretting cycle and it only occurs when specific criteria are met in the fretting system: reduction in the coefficient of friction and the self-excited vibration of the structure. In this study, 304 SS steel samples are tested within a fretting rig apparatus that produces high frequency noise. In addition to spectral analysis of the noise produced, the dynamic response of the self-excited response of the system is developed. The combination of spectral data and structural dynamics data may allow for better correlation between noise and the prediction of wear in dry metal-to-metal contacts. T. Jibiki and M. Tamura, “A basic study of friction noise caused by fretting,” Wear 251, 1492–1503 (2001).
Sound power from coupled structures using elementary radiators
Authors: Ostergaard Sarah A. , Blotter Jonathan D. , Gilbert Suzanna , Sommerfeldt Scott D. , Bates Trent P.
Published: May 2022

Sound power measurements are of interest in numerous applications, and several methods are available for obtaining the sound power of a system. A recent method that has been developed, referred to as the Vibration-Based Sound Power (VBSP) method, utilizes vibration measurements obtained from a Scanning Laser Doppler Vibrometer (SLDV). The VBSP method has previously been used to obtain the sound power radiated from flat plates, cylindrical shells and curved plates. This paper will present further developments to extend VBSP measurements to multiple coupled structures and investigate the acoustic coupling effects that may exist. Two coplanar flat plates separated by a distance d were modeled using the boundary element method. The sound power was determined within the boundary element software and the structural velocities were also exported and processed using the VBSP method. Computational and experimental results will be shown to demonstrate abilities and limitations for the VBSP method to accurately determine the radiated sound power for coupled structures. [Funding for this work was provided by the National Science Foundation (NSF).]
Beneath the surface: Interactions of subthreshold gestural systems
Authors: Tilsen Sam
Published: May 2022

Control of articulatory movements is dominated by gestural systems whose activation states are above a threshold. These highly active systems strongly drive activity in spatial fields encoding articulatory targets, thereby governing the kinematics of vocal tract systems. In the presence of these strong forces, gestural systems with below-threshold activation exert weaker, sometimes opposing forces on target fields. These subtle forces can generate consistent subcategorical patterns of phonetic variation conditioned on the co-activation of gestural systems. Depending on the relations between targets of gestural systems and their force distributions, this variation can give rise to different types of long-distance phonological patterns.
Understanding anticipatory speech postures: does coarticulation extend outside the acoustic utterance?
Authors: Krause Peter A.
Published: May 2022

Multiple studies strongly suggest that anticipatory coarticulation has a planned component. Speakers forced to begin an acoustic utterance before knowing all details of how it will unfold show reduced coarticulatory influences from those initially unknown speech segments. Therefore, anticipatory coarticulation as we currently understand it may reflect a more general process whereby speech acts that are currently planned, but whose acoustic consequences remain in the future, bias current articulator positions. This more general process could be in effect even before an utterance is acoustically active. The present talk will review the author’s recent work in anticipatory speech postures. Specifically, these findings suggest that speakers bias their lips to anticipate utterances yet to be acoustically initiated, in a way that tracks currently available information. In laboratory tasks, speakers primed with just the initial consonant or nuclear vowel of an upcoming monosyllabic utterance shape their lips to reflect this priming. Similarly, speakers in natural conversation produce anticipatory lip postures while awaiting their turn, but only when the intended utterance is quite short. The conceptual links between these findings and anticipatory coarticulation will be discussed.