bluuebunny/crossref_metadata_2025 huggingface dataset:
Decoding MEG responses to musical pitch reveals the dynamic emergence of tonal structure in human cortex
Authors: Sankaran Narayan , Carlson Thomas A. , Thompson William Forde
Published: April 2019

Tonal music is characterized by a hierarchical structuring of pitch, whereby certain tones appear stable and others unstable within their musical context. Despite its prevalence, the cortical mechanisms supporting such a percept remain poorly understood. We examined the neural processing dynamics underlying pitch-structure in Western Tonal Music. Listeners were presented with tones embedded within a musical context whilst their magnetoencephalographic (MEG) activity was recorded. Using multivariate pattern analysis, decoders attempted to classify the identity of tones from their corresponding MEG activity at each peristimulus time-sample, providing a dynamic measure of their cortical dissimilarity. Time-evolving neural distinctions were then compared with the predictions of several acoustic and perceptual models. Following the onset, a temporal evolution was witnessed in the representational structure in cortex. While MEG dissimilarities between tones initially corresponded to their fundamental frequency separation, distinctions beyond 200 ms reflected their status within the hierarchy of perceived stability. Transposing dissimilarities corresponding to this latter period into different keys, neural relations between keys correlated with the well-known circle of fifths. Convergent with fundamental principles of music-theory and perception, results detail the dynamics with which the complex perceptual structure of Western tonal music emerges in human cortex within the timescale of an individual tone.
Referee whistles Part II—Outdoor sound power assessment
Authors: Murphy William J. , Tasko Stephen M. , Finan Donald , Meinke Deanna K. , Stewart Michael , Lankford James E. , Campbell Adam R. , Flamme Gregory
Published: April 2019

Referee whistles have been suggested as a significant contributor to noise-induced hearing loss. Thirteen models of sport whistles were tested for sound power with a 3-m hemispherical array of 19 microphones. The whistler produced nine tweets of low, medium, and high effort with two samples of each whistle model. Sound power levels ranged between 74 and 115 dB re 1 pW. The low, medium, and high effort tweets had average power levels of 85 ± 6 dB, 100 ± 6 dB, and 110 ± 4 dB, respectively. Preliminary damage-risk analysis of the whistle impulses yield varied estimates for the allowable number of tweets before auditory damage might be expected. For the Auditory Hazard Assessment Algorithm, between 4 and 66 tweets may exceed the daily exposure threshold. Based upon the amount of eight-hour equivalent A-weighted energy, approximately 120 to 500 tweets would exceed the daily 85 dBA exposure limit. The directivity of the sound power measurements will also be examined, and risk of hearing loss will be discussed.
Acoustic streaming in a channel a moderate streaming Reynolds number
Authors: Thompson Charles , Vanegas Jairo , Perkins Russell , Norceide Flore , Alvarez Ivette , Chandra Kavitha
Published: April 2019

In this work, the generation of acoustic streaming in a rigid walled channel is examined. At low values of the streaming Reynolds number, the time-averaged fluid motion in the channel follows that given by Rayleigh. However, departure from the aforementioned result ensues as the magnitude of the streaming Reynolds number increases. Higher order nonlinear corrections to the Rayleigh streaming solution is given and are expressed in terms of a regular perturbation sequence in nondimensional particle amplitude. It is shown that the reduction in the amplitude of the axially directed streaming velocity is a function of the streaming Reynolds number.
Attention versus adaptation in processing talker variability in speech
Authors: Lim Sung-Joo , Tin Jessica , Qu Allen , Perrachione Tyler K.
Published: April 2019

Speech processing is slower when listening to speech from multiple talkers compared to one continuous talker. Prior studies of talker variability mostly compared listening to long blocks of a continuous talker versus blocks where talkers constantly switch. It is thus unclear whether differences in processing efficiency are better understood as facilitation from perceptual adaptation to a talker or as interference from the attentional disruption caused by abrupt talker switches. It is also unclear how processing a single talker’s speech becomes more efficient with ongoing exposure. Here, we examined how speech processing speed depends on preceding exposure to a talker. Listeners performed a speeded word identification task, in which they heard each talker’s speech for 2–7 consecutive trials before the talker switched. Word identification was slowest when the talker switched and was expedited after a single exposure to a talker. However, additional exposure to a talker did not further improve word identification speed. More frequent talker switches in the preceding speech also led to slower subsequent word identification. Our findings suggest that speech processing efficiency does not depend on perceptual adaptation to the preceding talker; rather, slower speech processing after a change in talker reflects the costs of attentional reorientation.
Changes in the phonetics of German language learners over a semester
Authors: Taft Benjamin N. , Elliott Lauren
Published: April 2019

We compare the acoustic phonetics of German language learners at the beginning and end of a college semester. Participants recorded three utterances of five example sentences in the first and last months of the semester. Results from the early recordings documented that language learners were intermediate between native speakers and naive speakers in at least two different acoustic contexts. The voice onset time (VOT) of the /f/ sound was short in native speakers (more /f/-like) and long in naive speakers (more /v/-like). Similarly, the vowel space traversed during the vowel sound of "viel" had a smaller area in native speakers than in naive speakers. We predict that, on average, language learners will show change in both their VOT and their vowel space, becoming more similar to native speakers, while naive speakers will not show any change. We will use paired t-tests to compare the early and late productions from each speaker. We will also expand the array of acoustic features that we will examine to include additional vowel and consonant sounds.
R. Bruce Lindsay Award 2019: Adam Maxwell
Authors: Maxwell Adam
Published: April 2019

The R. Bruce Lindsay Award (formerly the Biennial Award) is presented in the Spring to a member of the Society who is under 35 years of age on 1 January of the year of the Award and who, during a period of two or more years immediately preceding the award, has been active in the affairs of the Society and has contributed substantially, through published papers, to the advancement of theoretical or applied acoustics, or both. The award was presented biennially until 1986. It is now an annual award.
Acoustics simulations to inform the designs of large worship and entertainment spaces to the client and contractor
Authors: Woolworth David S.
Published: April 2019

Computer based acoustical simulations can quickly communicate important information in visual and audible formats that have a strong and immediate impact on the non-acoustician decision makers and designers of a project. Two large spaces were modeled (>6000 m3), one renovation, one new construction; simulations were used to help better understand the consequences of different design approaches for amplified sound and acoustical design, as well as handing value engineering response in a timely manner. Attention is given to the modeling’s role in helping to sort out the paradigms of perception of the project team and then to inform the design options of the clients and end users.
Room acoustic simulation as a means to affect a musical composition for a location specific performance
Authors: Skorski Edwin S. , Landis Steven J.
Published: April 2019

Computer model simulations of existing interior spaces are often generated to document and analyze room acoustic characteristics. In this case study, a large, multi-tiered public atrium is analyzed for its potential use as a performance space. Furthermore, the analysis is also used to transform an existing musical composition into a location specific performance piece. The computer simulation highlights acoustic characteristics believed to be good for musical performance as well as those considered defects. Taking into account the unique room acoustic qualities of this non-traditional performance space, an existing musical composition is rewritten resulting in a space-dependent arrangement. Musical variables transformed due to the analysis include tempo, pacing, register, as well as source and receiver positions. Of specific interest are the room characteristics typically considered acoustic defects which are purposefully exploited to strengthen the impact of the performed piece. These include non-optimal reverberation times, sound focusing, and echoes. Acoustic analysis of the room and recordings of the composition will be presented.
Evaluation of shape grammar-generated diffuser arrays
Authors: Hsu Timothy , Dessi-Olive Jonathan
Published: April 2019

This paper proposes a means of evaluating arrays of quadratic residue diffusers (QRDs) generated through a grammar-based generative design method. Design processes for architectural acoustics are often highly conventional: acoustical designers have preferred to use historical examples, known equations, and standard principles of performative success. This is particularly true for surface treatments using diffuser products that are aggregated in ways that perform sufficiently but are visually predictable and monolithic. In the first phase of this project, a shape grammar approach to design acoustic diffuser arrays was proposed as a means of addressing the issue of design homogeneity in architectural acoustics and to break current habits of uniform deployment of diffusion treatments in spaces. A set of shape rules were proposed that generate non-uniform and sometimes surprising arrays of QRDs. This paper aims to expand demonstrate phase two, which includes the following: (1) clarification and further development of shaper grammar rules, (2) proposal of initial methods to evaluate the acoustic performance of these arrays, and (3) calculation of quantitative metrics. Numerical simulations will show time and directivity responses for these shape grammar generated diffuser arrays. Furthermore, diffusion and scattering coefficients will be presented as well as other proposed evaluation metrics for these larger arrays.
Direct error in constitutive equation formulation for inverse problems in time harmonic elastography
Authors: Barbone Paul E. , Babaniyi Olalekan A. , Yengul Sanjay S.
Published: April 2019

Shear wave imaging techniques allow the evaluation of rigidity and viscosity of tissues locally within a material. From an inverse problem perspective, the approach is quite attractive insofar as it provides a densely sampled displacement field in the interior of the object from which to invert for material properties. We consider several challenges related to elastic wave inverse problems arising in acoustic radiation force imaging. First, we validate an axisymmetric viscoelasticity model suitable for some applications of acoustic radiation force imaging. Second, we consider reconstructing lateral displacement components from measured axial displacement components. Finally, we present a new variational formulation, the direct error in constitutive equation formulation, for inverse problems in time harmonic viscoelastic wave propagation with full-field data. The formulation relies on minimizing the error in the constitutive equation with a momentum equation constraint. Numerical results on model problems show that the formulation is capable of handling discontinuous and noisy strain fields and also converging with mesh refinement for continuous and discontinuous material property distributions. Applications to MRE and ARFI measured wave data are considered.
Efficient sub-diffraction passive cavitation imaging
Authors: Schoen Scott J. , Zhao Zhigen , Arvanitis Costas
Published: April 2019

Acoustic localization of microbubbles offers a unique method to assess vascular structure and function noninvasively. To this end, passive imaging of the acoustic cavitation with the angular spectrum method (AS-PCI) is appealing as it is inherently fast and frequency-selective and thus allows stable cavitation activity to be isolated from other scatters via the bubbles’ harmonic emissions. However, diffraction imposes a physical limitation on the resolution of acoustic imaging systems, which is typically on the order of millimeters for PCI. To enable rapid visualization of vessel structures with diameters of few hundreds of microns, we present a technique based on the AS method for fast super-localization (SL) of multiple, spatially separated bubbles that is 100-fold more efficient than time domain techniques employed for resolution improvement. We demonstrate, via experiments and numerical simulations, that it is possible to super-localize multiple bubbles within a single image and resolve vessels with diameters 10 times smaller than the diffraction limit (300 µm vs. 3 mm, respectively). Furthermore, successive super-localization of hundreds of microbubbles with the proposed SL-AS-PCI method allowed visualization of three-dimensional vessel structures within a few seconds on ordinary hardware. SL-AS-PCI holds great promise for efficient diagnosis of diseases associated with abnormal vasculature.
Orientation-dependent anisotropy of acoustic properties of tendons at micrometer scale
Authors: Ogawa Takuya , Yang Bin , Lam Po , Yamaguchi Tadashi , Sigal Ian A. , Mamou Jonathan
Published: April 2019

Tendons are bands of fibrous connective tissue connecting muscles to bones. They are composed of parallel arrays of collagen fibers closely packed together which makes them highly anisotropic. The anisotropy of the acoustic properties of tendons was investigated at an ultra-fine resolution (< 7 μm) using quantitative acoustic microscopy (QAM). Chicken tendons were fixed (formalin) while loaded longitudinally, then cryosectioned (16-µm) at several orientations (every 15 deg) from parallel (i.e., 0 deg) to perpendicular to the fibers (i.e., 90 deg). Two regions of two sections per angle were scanned using a QAM system operating at a center frequency of 250 MHz yielding a total of 28 QAM datasets which were processed to yield two-dimensional (2D) maps of the bulk modulus, mass density, acoustic impedance, and speed of sound for each scanned region. Acoustic parameters were averaged within each 2D map and mean and standard deviations computed at each angle. Results demonstrated a strong acoustical anisotropy. For instance acoustic impedance increased from 1.68 ± 0.08 to 1.87 ± 0.19 MRayl between 0 and 75 deg. Similarly, the speed of sound increased from 1686 ± 90 to 1958 ± 186 m/s between 0 and 75 deg. These results demonstrate the value of QAM to investigate the anisotropy of tissue microstructure and pave the way for using it to characterize other soft tissues with complex three-dimensional fiber orientations. [Work supported in part by NIH Grants EY023966 and EY028662.]
Computational viscothermal acoustic study of micro-electro-mechanical systems (MEMS) perforated plates
Authors: Naderyan Vahid , Raspet Richard , Hickey Craig , Mohammadi Mohammad
Published: April 2019

Micro-perforated plates (MPP) are widely used as sound absorption materials in many noise control applications. Acoustic properties of the MPPs have been theoretically and experimentally studied for many years. The results of these studies are often used in the studies of MEMS devices with perforated plates. However, there exist differences in the physical dimensions of MPPs and MEMS perforated plates. The typical MPP perforation radius is in the range of 1 mm to 1 cm. For these dimensions and audio frequencies, the shear wave-number is much larger than 1. The dimensionless shear wave-number, which is an unsteady Reynolds number, is a measure for the ratio between inertial and viscous effects. Hence for typical MMPs, the inertial effects are dominant. However, the typical hole radius in the MEMS perforated plates is below 20 µm corresponding to subunit shear wave-numbers. Therefore, in MEMS perforated plates, the viscous effects are the dominant part of the impedance. In addition, typical MPPs have low porosities on the order of 1%, whereas typical MEMS perforated plates have high porosities in the range of 25% to 75%. In this work, viscous and thermal losses and also the end effects of the MEMS perforated plates are studied using the finite element method.
Synergy of spectral and spatial segregation cues in simulated cocktail party listening
Authors: Rodriguez Brianna , Lee Jungmee , Lutfi Robert
Published: April 2019

An approach is borrowed from Measurement Theory [Krantz et al., Foundations of Measurement (1971), Vol. 1] to evaluate the interaction of spectral and spatial cues in the segregation of talkers in simulated cocktail-party listening. The goal is to determine whether mathematical transformations exist whereby the combined effect of cues can be additively related to their individual effects. On each trial, the listener judged whether an interleaved sequence of 4 vowel triplets (heard over headphones) was spoken by the same BBBBBB… or different ABAABA… talkers. The talkers had nominally different fundamental frequencies and spoke from nominally different locations (simulated using Kemar HRTFs). Natural variation in these cues was simulated by adding a small, random perturbation to the nominal values independently for each vowel on each trial. Psychometric functions (PFs) relating d’ performance to the difference in nominal values were obtained for the cues presented individually and in combination. The results revealed a synergistic interaction of cues wherein the PFs for cues presented in combination exceeded the simple vector sum of the PFs for the cues presented individually. The results are discussed in terms of their implications for possible emergent properties of cues affecting performance in simulated cocktail-party listening. [Work supported by NIDCD R01-DC001262].
Informational masking of speech analogues by intelligible and non-intelligible but acoustically similar interferers
Authors: Summers Robert J. , Roberts Brian
Published: April 2019

Informational masking of target speech is generally greater when the interfering speech is intelligible than when it is not (e.g., speech from an unfamiliar language), but the relative contributions of acoustic-phonetic and linguistic interference are often difficult to assess owing to acoustic differences between interferers (e.g., different talkers). This study used three-formant analogues (F1 + F2 + F3) of natural sentences as targets and interferers. Target formants were presented monaurally (F0 = 120.3 Hz) either alone or accompanied with the contralateral ear by interfering formants from another sentence (F0 = 151.5 Hz); a target-to-masker ratio (TMR) between ears of 0, 6, or 12 dB was used. Interferers were either intelligible or rendered non-intelligible by delaying F2 and advancing F3 by 150 ms relative to F1, a manipulation designed to minimize spectro-temporal differences between corresponding interferers. Target-sentence intelligibility (keywords correct) was 67% when presented alone but fell considerably when a non-intelligible interferer was present (49%) and significantly further when the interferer was intelligible (41%). The changes in TMR produced neither a significant main effect nor an interaction with interferer type. The results suggest that although linguistic factors contribute to informational masking, interference with acoustic-phonetic processing of the target can explain much of the impact on intelligibility. [Work supported by ESRC.]
Audio and visual distance perception of familiar and unfamiliar objects using Wave Field Synthesis and a stereoscopic display
Authors: Richie Sarah , Braasch Jonas
Published: April 2019

Object distance perception can be influenced both by auditory and visual cues. This work seeks to examine the influence of both perceptual domains for familiar and unfamiliar auditory and visual stimuli. For example, an alarm clock is a familiar object and a generic vibrating sphere is an unfamiliar object because the distance cannot be estimated from known dimensions. A Wave Field Synthesis (WFS) system and a stereoscopic large screen display using shutter glasses was used to create the virtual objects. Utilizing WFS allowed for sources to be placed virtually behind and in front of the speaker array. Cues were presented audio only, visual only or audio and visual simultaneously. Participants were asked for the estimated depth of the object while randomizing the above scenarios. This work expands upon a previous study [J. Acoust. Soc. Am. 137, 2374] that suggested that the visual cues tend to dominate perception even when auditory cues are available. One goal of the new study is to investigate if finding holds true and if the listener is presented with more salient cues that also allow for head movements. In the previous study, the virtual environment was based on static Head-Related Transfer Functions (HRTFs).
Impact of spatial variability and masker fringe on detectability of brief signal
Authors: Wang Michelle H. , Gilkey Robert H. , Simpson Brian
Published: April 2019

Seemingly, there should be a close relationship between spatial release from masking and sound localization, but this is not always the case. For example, in binaural detection, randomizing the spatial parameters of the target or masker from trial to trial has little impact on threshold. In contrast, Simpson (Ph.D. dissertation, 2011) found that left/right localization judgments for a 60-ms target masked by a simultaneous 60-ms noise were considerably less accurate (equivalent to 10-dB reduction in SNR) when the location of the masker varied randomly from trial to trial than when the masker location was fixed. However, when a forward masker fringe was added, so that the noise was turned on 500 ms before the target, the impact of location variability was very small (about 1 dB, comparable to the detection literature). To determine if the presence of masker fringe could have limited the impact of spatial variability in previous detection experiments, the current study examines the effect of masker fringe and both target and masker spatial variability on detectability in conditions comparable to those of Simpson. The results will be compared to previous findings and models reported in the binaural detection and sound localization literature.
Comparison of localization assessments for hearing protection
Authors: Brandewie Eugene , Dittberner Andrew
Published: April 2019

Sound localization is a critical component of the assessment of situational awareness for hearing protection devices (HPDs). A new standard is being developed for the assessment of sound localization in the horizontal-plane concerning head-worn devices. One of the methodologies offered by this standard is a quick and easy-to-use paradigm for rapid prototyping of hearing devices. This study compared the results of this new assessment methodology with a more traditional assessment of horizontal-plane sound localization. Four devices (including open-ear) were tested on normal-hearing individuals using both paradigms. A comparison of localization errors, front-back-reversals, hardware for data collection set-ups, and expected data collection time is presented. Results suggest comparable differences between the two methodologies.
Difference limens for noise bandwidth discrimination in listeners with normal and impaired hearing
Authors: Alexander Joshua M.
Published: April 2019

Frequency-lowering (FL) in hearing aids is often used to move inaudible high-frequency energy from sibilant fricatives to spectral regions where hearing better. Clinically, FL settings that maximize the spectral separation between these sounds, which can be modeled as bands of noise, are assumed to maximize discrimination between them and other speech contrasts. The purpose of this study was to quantify the minimum spectral differences for normal-hearing and hearing-impaired listeners to discriminate between bands of frozen noise. Noise bands corresponded to the average frequency and bandwidth of sibilant fricatives after undergoing FL using settings appropriate for mild-to-moderate, moderately-severe, and severely-profound hearing losses. Noise bands differed on the low- and/or the high-frequency edges. Discrimination in normal-hearing listeners was constant across presentation level and the three frequency ranges. Discrimination was also better for high-frequency edge differences. Neural excitation patterns generated from an auditory nerve model account for these findings. Neural excitation patterns generated for the three severities of hearing loss indicate that hearing-impaired listeners will rely heavily on spectral differences on the low-frequency edge and indicate that sibilant fricatives processed with FL will not be able to be discriminated solely on the basis of high-frequency edge differences. [Grant supported by Sonova USA, Inc.]
Can listeners reliably identify their preferred amplification profiles for speech listening?
Authors: Yun Donghyeon , Shen Yi , Zhang Zhuohuang
Published: April 2019

Personal hearing devices, such as hearing aids, may be fine-tuned for individual users’ preferences by allowing them to self-adjust the amplification profiles. The purpose of the current study was to compare two self-adjustment methods in terms of their test-retest reliability. Both methods estimated preferred amplification profiles in six octave-frequency bands using the method of adjustment. In one method (method A), listeners adjusted the gain in one of six frequency bands using a programmable knob on a given trial; while in the other method (method B), listeners adjusted the gains in all six bands simultaneously according to a linear model using the same programmable knob. Ten normal-hearing listeners participated in the study. The experiment was completed in two test sessions, at least one week apart. During each session, the preferred amplification profile was estimated using both methods. Running speech in quiet or in speech-shaped noise was used as the test stimuli. At the beginning of each method, the initial amplification profile was generated randomly with the gains drawn from a uniform distribution spanning between -25 and 25 dB. The test-retest reliability for method B was better than method A. For method B, the test-retest reliability was better at lower signal-to-noise ratios.
3D printed pinna embedded in circumaural hearing devices for spectral cue preservation
Authors: Acosta Carrasco Carlos , Krull Vidya , Dittberner Andrew , Wicker Ryan
Published: April 2019

Innovations in additive manufacturing [three-dimensional (3D) printing] have allowed for the fabrication of objects as complex as the human ear. The visible part of the human outer ear (pinna) serves as a funnel and a natural filter for incoming sound. Spectral cues generated by the pinna help with auditory localization and externalization. In an attempt to preserve spectral cues when using circumaural hearing devices, the present work explored the use of 3D printing to fabricate individualized pinna within custom-designed and fabricated hearing devices. Through 3D scanning, a computer aided design (CAD) model of a pinna from an anthropometric mannequin was generated to replicate human pinnae. Multiple 3D printing technologies were used to fabricate the CAD model, investigating different material options, dimensional accuracies, and overall printing costs. The fabricated pinnae were subjected to acoustic testing to assess spectral cue preservation by comparing mannequin head-related transfer functions obtained with the printed pinnae to those with the original. A sample circumaural hearing device with the pinna embedded within it was then designed, fabricated, and subjected to the same acoustic testing for comparison. Results from testing will be described within the context of providing individualized circumaural hearing devices that assist with spectral cue preservation.
Exploring the relationship between sound localization and individual use of spectral and temporal cues among hearing-impaired listeners
Authors: Ellis Gregory M. , Souza Pamela
Published: April 2019

When locating a sound source, listeners are expected to rely more on spectral cues for elevation and temporal cues for azimuth. This work investigates whether sound localization ability can be predicted by individually-measured use of spectral and temporal cues. Participants were older adults with sensorineural hearing loss. Sound sources for the localization task were created in a virtual room, using a mix of virtual and physical loudspeakers in the front hemifield of the listener. Sources were distributed evenly between ±90 deg azimuth and ±20 deg elevation. The signal was a 1 s broadband 4-Hz amplitude-modulated noise. To assess the relationship between localization ability and use of spectral and temporal cues, listeners performed cue weighting and cue discrimination tasks. In the cue weighting task, listeners identified synthetic speech sounds that varied spectro-temporally. The cue discrimination task measured the smallest detectable difference in either spectral or temporal information among the same set of ambiguous speech sounds. Together, these tasks form a cue profile which identifies whether the listener relies to a greater extent on temporal or spectral cues. Older hearing-impaired listeners varied in their ability to localize sounds. Localization results will be discussed in the context of cue profiles and audiometry. [Work supported by NIH.]
Experiment on the relationship between the dynamic range of hearing and psychophysical tuning curves
Authors: Brennan Marc
Published: April 2019

In this study, we hypothesized that improving the dynamic range of hearing for adults with hearing loss would improve spectral resolution by providing better audibility across frequency and—due to the higher sensation level—improved phase locking. However, limited outer hair cell (OHC) function and spread of excitation likely curtail the benefit of improved audibility on spectral resolution. In this experiment, the relationship of the dynamic range of hearing to measures of psychophysical tuning curves was quantified for 13 adults with hearing loss. Twenty-one adults with normal hearing served as controls. A dynamic range of hearing was manipulated by systematically adjusting hearing-aid gain and compression ratios. To better understand the mechanisms that support the encoding of spectral resolution with amplification, the behavioral data were modeled using a cochlear excitation model. For most listeners, the psychophysical tuning curves were similar regardless of changes in the dynamic range of hearing. For a subset of participants, tuning on the low frequency side improved as the dynamic range of hearing was increased—which could be accounted for in the model by residual OHC function. The model better accounted for unaided than aided measures of tuning.
A software controlled audiometric setup to predict types of hearing loss from types of response delays
Authors: Biswas Amitava , Goshorn Edward L. , Goshorn Jennifer
Published: April 2019

Diagnosis of certain types of non-organic hearing loss is often confused with organic hearing loss. A software controlled audiometric setup has been designed by the authors for this purpose. Its salient features are (1) partially randomized step sizes, (2) partially uncorrelated increase and decrease in the stimulus intensity after each response or no response of the subject, (3) recording of corresponding response delays of the subject, and (4) providing audio-visual feedback. Its sensitivity, specificity, and applications in clinics and the industry will be discussed.
Development of vibrational metrics for internal damage scenarios of a scaled Transnuclear-32 dry storage cask for spent nuclear fuel
Authors: Lin Kevin Y. , Mobley Joel , Prather Wayne E. , Lu Zhiqu , Priyadarshan Gautam , Gladden Josh R.
Published: April 2019

The assessment of the internal structural integrity of dry storage casks for used high burnup nuclear fuel assemblies is of critical importance before transporting these to permanent repositories. The large size and structural complexity of the Transnuclear-32 (TN-32) cask as well as the inability to access its interior make this a challenging task. To address these difficulties, we use an active acoustics approach to develop metrics that are sensitive to the internal configuration of these casks. A 6:1 scaled model of the TN-32 cask was constructed in order to study the internal configuration of the fuel assemblies including various damage scenarios. Each mock-up fuel assembly consists of bundled steel rods, and their structural failure is mimicked by steel shot of equal weight. This talk will report the amplitude- and phase-based active acoustics metrics that we developed to characterize different levels of internal damage. Our studies indicate that vibrometric signatures of various internal conditions can be measured using sources and sensors mounted on the exterior shell. Our current methodology is sensitive enough to detect structural failures at the single fuel assembly level. [Work supported by DOE NEUP Award No. DENE0008400.]
Working gases based scaling-down limitations for thermoacoustic coolers: Miniaturization approach
Authors: Abdelrahman Anas M. , Zhang Xiaoqing
Published: April 2019

Regarding miniaturization of thermoacoustic coolers for thermal management purposes, working gases play a key role as the primary media responsible for producing the so-called “thermoacoustic effect” with their interaction with solid media (i.e., secondary media) within stacks or regenerators. However, the role of working gases in limiting scaling-down of thermoacoustic coolers still needs more investigations compared to addressed operational parameters (i.e., mean pressure, temperature difference across stack, etc.). In the present study, a theoretical computational analysis, based on published literature work, would be conducted to investigate allowable minimum sizes of standing-wave thermoacoustic coolers under the effects of working gases thermo-physical properties with considering adverse effects limitation of thermal conduction losses. Different working gases including air and either pure or mixture noble gases have been used for such geometrical scaling-down analysis under specific operating conditions. Moreover, cooling power was focused here as the more desirable performance indicator rather than the efficiency. The results had revealed the cooling capability at different scale levels based on different working gases, which make gases properties significantly contribute to scalability of thermoacoustic coolers to meet the cooling needs for micro-electronics. In addition, more research work will be devoted to other scaling-down issues of thermoacoustic systems.
Micro-electro-mechanical system multi-resonant accelerometer for auditory prosthetics
Authors: Hake Alison , Grosh Karl
Published: April 2019

Low usage of auditory prosthetics such as hearing aids can be attributed to several factors including appearance, stigma, acoustic feedback, and poor performance in noisy environments. Cochlear implants suffer from similar stigma; furthermore, external components of the system must be removed for sleeping, bathing, and physical exercise. Designing a completely implantable system that includes a sensor placed in the middle ear can mitigate these issues. Our approach is to use a miniature piezoelectric accelerometer to sense the vibration of the middle ear ossicles rather than employing an external or subcutaneous microphone to sense incoming sound. Results of our previous work showed the potential of this approach using a traditional single-resonance sensor. We seek to improve the low-frequency input referred noise (IRN) of the system by using a new architecture consisting of an array of piezoelectric MEMS beams with different resonant frequencies. The beams are connected electrically in a manner that increases the system sensitivity over the bandwidth of interest, thereby decreasing the IRN. Preliminary analytic studies have illustrated that 10 parallel-connected beams can improve the IRN by approximately 45 dB at 100 Hz. This method could further miniaturize sensors capable of detecting ossicular vibration from 100 Hz to 8 kHz.
Method for low frequency sound reflection coefficient measurements in a compact space
Authors: Peng Xiuyuan , Li Junfei , Shen Chen , Lenihan Kiegan , Cummer Steven
Published: April 2019

Here, we present a method to measure the quasi-normal reflection coefficients of sound absorbing materials in a compact space. A short incident sound pulse (length < 3ms) is generated by a deconvolution method with the source speaker. Then, a stage-mounted microphone moves across the material surface and records the total (incident + scattered) sound field. By comparing the sound field with and without the presence of the sound absorbing material, the frequency-dependent reflection coefficients can be derived by extracting the corresponding frequency components from the sound pulse. Using this method, we can calculate the reflection coefficients of a 2 ft. by2 ft acoustic panel from 300 Hz to 2500 Hz within a 2 m by2 m by3 m lab space without anechoic coatings. Moreover, this method enables us to investigate the spatial inhomogeneity of the sound absorbing material by studying the amplitude/phase variation of reflection coefficients across the material surface. Compared with conventional measurement techniques for reflection/absorption coefficients, our method has the advantages of low cost, minimal requirements for the measurement environment and the ability to measure the reflection coefficients at different locations. The proposed method can be favorable for measuring reflection coefficients of two-dimensional acoustic panels/metamaterials at low frequencies.
Audio and ultrasonic frequency response measurements using regularized inverse filtering
Authors: Sinelnikov Yegor , Boyden Andrew , Lavery Richard , Calvarese Russell
Published: April 2019

Skyrocketing growth in digital voice communication technology prompts inclusion of ultrasonic microphones in modern smartphones. Inaudible ultrasonic waves provide safe and effective way for ambient intelligence in indoor environments. It is important to measure microphone response over combined audio and ultrasonic range. Conservative measurements based on frequency sweep present signal equalization challenge. Most ultrasonic tweeters produce narrowband ultrasonic tones, while audio speakers resonate below 1 kHz. We present a simple methodology based on emission of specially constructed noise stimulus that overcomes this limitation. The Ole Wolf 25 x16 mm 1 W 8 Ω speaker connected to B&K power amplifier delivered the stimulus. High frequency B&K type 2670 reference microphone was used to record responses at 192 kHz. Experiments were performed in two stages. First, the blue noise was emitted, its response was recorded, and new stimulus with flat spectra between 15–25 kHz was derived using regularized inverse filtering technique. Second, constructed stimulus was emitted and recorded by reference microphone and device under test. The frequency response was derived and found in good agreement with conventional stepped sweep measurements.
Improving autonomous vehicle safety—The use of convolutional neural networks for the detection of warning sounds
Authors: Wagner Ethan , King Eoin A.
Published: April 2019

In cities across the world everyday, people use and process acoustic alerts to safely interact in and amongst traffic. With the advent of autonomous vehicles (AVs), the manner in which these new vehicles can use these acoustic cues to supplement their decision making process is unclear. This will be especially important during the prolonged period of mixed vehicles sharing the road. One solution may lie in the advancement of machine learning techniques; it has become possible to "teach" a machine (or a vehicle) to recognize certain sounds. This paper reports on an ongoing project with the objective of identifying emergency vehicles sirens in traffic and alerting the vehicle to take rapid evasive action. In particular, we report on the use of a deep layer Convolutional Neural Network (CNN) trained to recognize emergency sirens. We retrained a CNN (AlexNet) to recognize sirens in real time. To utilize this network, samples from the ESC-50 dataset for environmental sound classification were processed and each converted to a spectrogram. This CNN can be used in conjunction with a microphone array to accurately recognize sirens in traffic and identify the direction from which the emergency vehicle is approaching.
On the viability of the complex-intensity-based near-field acoustical holography method
Authors: Goates Caleb B. , Sommerfeldt Scott D. , Gee Kent L. , Neilsen Tracianne B.
Published: April 2019

Because of the instrumentation difficulties of Fourier acoustical holography, it is desirable to find a holography method that does not require reference signals during array scanning. Among the methods that have been investigated to remove the need for references are those based on acoustic intensity measurements, including the complex-intensity-based near-field acoustical holography (CIBNAH) method [A. Nejade, J. Sound Vib. 333(16), 3598–3608 (2014); Appl. Acoust. 116, 348–356 (2017)]. The CIBNAH method has previously been applied to simple contrived sources and real-world machinery but has not been verified using analytical source models. This work shows the application of CIBNAH to an analytical model of a simply-supported plate, revealing key shortcomings of the method. The theory behind CIBNAH is discussed in light of these shortcomings. It is shown that while CIBNAH may be useful for finding radiation hot spots, it is not an adequate method to overcome the need for references in scan-based acoustical holography. [Work supported by NSF.]
Quantifying ocean acoustic propagation uncertainty due to environmental uncertainty from ship-noise inversion
Authors: Dosso Stan E. , Tollefsen Dag
Published: April 2019

This paper considers the uncertainty in underwater acoustic propagation predictions that results from uncertainty in oceanic environmental parameters (water column and seabed) as estimated from acoustic inversion methods. The approach is general but is considered here for the inversion of acoustic fields from ships-of-opportunity, which represents a convenient and unobtrusive approach to environmental assessment, but with significant uncertainties for some environmental parameters. In this work, environmental uncertainties are quantified using trans-dimensional (trans-D) Bayesian inversion based on reversible-jump Markov-chain Monte Carlo sampling. Trans-D inversion considers the number of sediment layers in the seabed and/or the number of points defining the water-column sound-speed profile as unknown parameters, sampled probabilistically in the inversion. This approach numerically characterizes the posterior probability density of the environment using a large ensemble of dependent random samples of the model. Predicting acoustic propagation for a much-smaller, randomly-chosen subset of these model samples transforms environmental uncertainty to propagation uncertainty, which can be characterized spatially with standard statistical measures (standard deviation, credibility intervals, etc.). The approach is illustrated using simulations and noise from a large commercial ship recorded on an a horizontal array of hydrophones as part of the 2017 Seabed Characterization Experiment (SBCEX17) at the New England Mud Patch.
Photoacoustic tomography in a clinical linear accelerator for quantitative radiation dosimetry
Authors: Johnstone David A. , Cox Michael T. , Ionascu Dan , Lamba Michael A. , Dumoulin Charles L. , Mast T. Douglas
Published: April 2019

Cancer is the second leading cause of death in the United States. Approximately half of all cancer patients receive radiation therapy, in which linear accelerators are used to deliver high doses of x-ray radiation to tumors, inducing cell death. X-ray energy deposition causes pressure changes that produce acoustic signals due to the photoacoustic effect. Here, clinical x-ray beams were directed at test objects made of antimonial lead and other metallic materials within a water tank. Photoacoustic signals were measured using a calibrated broadband hydrophone and validated using simulations in k-Wave. Linear and two-dimensional synthetic apertures were formed by mechanically scanning the x-ray source and test object within a single plane. Tomographic images of test objects, reconstructed from measured photoacoustic signals, show good agreement with object geometry. X-ray doses incurred by the test objects are mapped based on the reconstructed acoustic pressure sources and Grüneisen parameter of the material employed. Potential applications to in vivo dosimetry for x-ray and proton therapy, potentially enabling safer and more effective treatments, are discussed.
Repeatability of linear and nonlinear quantitative compression elastography in the breast
Authors: Barbone Paul E. , Gendin Daniel , Wang Yuqi , Nayak Rohit , Oberai Assad , Hall Timothy J. , Alizad Azra , Fatemi Mostafa
Published: April 2019

Compression elastography allows the precise measurement of large deformations of soft tissue in vivo. From a measured large deformation, an inverse problem for both the linear and nonlinear elastic moduli distributions can be solved. As part of a larger clinical study to evaluate NEMs in breast cancer, we evaluate the repeatability of linear and nonlinear modulus maps from repeat measurements. Within the cohort of 31 subjects scanned to date, several had repeated scans. These repeated scans were processed to evaluate NEM repeatability. In vivo data were acquired by a custom, digitally controlled, uniaxial compression device with force feedback. RF-data were acquired using plane wave imaging, at a frame-rate of 200 Hz, with a ramp-and-hold compressive force of 8N, applied at 8 N/s. A two-dimensional (2D) block-matching algorithm was used to obtain sample-level displacement fields which were then tracked at subsample resolution using 2D cross correlation. Linear and nonlinear elasticity parameters in the Blatz model of tissue elasticity are estimated using iterative optimization. Repeatability between both modes and elastic modulus maps is measured and compared. Preliminary results indicate that when images are acquired in the same region of tissue, the modulus maps are consistent. [Work supported by NIH R01CA195527.]