bluuebunny/crossref_metadata_2025 huggingface dataset:
Sound reproduction: Science in the service of art
Authors: Toole Floyd E.
Published: May 2014

The vast majority of music we enjoy is generated by loudspeakers of differing pedigree and propagated to our ears through spaces that can mostly be described as acoustically arbitrary. In spite of the obvious huge variations, humans have managed to not only enjoy reproduced music, but sometimes even to exhibit enthusiasm for it. Common acoustical measurements confirm the variations. Are they wrong? In double-blind subjective evaluations of loudspeakers in rooms, listeners exhibit strong and remarkably consistent opinions about the sound quality from loudspeakers. The challenge has been to identify those technical measurements that correlate with the subjective ratings. What is it that these listeners are responding to? A clue: it is not in the specification sheets of most loudspeakers, nor in a secret formula for room design. This tutorial will examine the acoustical properties of loudspeakers (the sound source), rooms (the acoustical conveyance), and listeners (the powerfully perceptive, and adaptable receptor). In some respects, our problems began when we started to make certain kinds of simplistic measurements. Two ears and a brain do not respond to complex sound fields the way an omnidirectional microphone and analyzer do. What our eyes see in these measurements is not always well-matched to what our ears hear.
Uncertainty in scattering coefficient measurements of sintered ceramic tiled surfaces
Authors: Bradley David T. , Russo Rhett , Sharma Ariana , Adelgren Jacob
Published: May 2014

The reflection of acoustic energy in an enclosed space can sometimes lead to undesirable effects, particularly if the reflection is relatively large in amplitude or delayed in time. To mitigate these effects, surfaces with non-planar geometries, which are known as diffusers, can be employed in an architectural space to improve the acoustical qualities of the space by attenuating these harsh reflections and by producing a more evenly distributed sound field. One of the standardized quantifiers used to characterize the effectiveness of a diffuser is the scattering coefficient, which is defined as the ratio of non-specularly reflected energy to total reflected energy. Measuring the scattering coefficient requires a carefully controlled acoustic testing facility known as a reverberation chamber. These chambers often have attributes that can be difficult to control (e.g., humidity) or that do not adhere to the standardized specifications (e.g., size). The current study explores the uncertainty associated with a series of measurements focused on testing the effectiveness of a new type of diffuser, which has been created using a novel ceramic sintering technique. The scattering coefficients of several of these ceramic surfaces have been measured in three different reverberation chambers with varying results.
Adaptive changes in acoustic characteristics of echolocation pulses emitted by Japanese house bats under artificial jamming conditions
Authors: Hiryu Shizuko , Takahashi Eri , Hyomoto Kiri , Watanabe Yoshiaki , Riquimaroux Hiroshi , Ohta Tetsuo
Published: May 2014

The echolocation behavior of Pipistrellus abramus during exposure to artificial jamming sounds during flight was investigated. Echolocation pulses were recorded using a telemetry microphone mounted on the bats' backs, and their adaption based on acoustic characteristics of emitted pulses was assessed in terms of jamming-avoidance responses (JAR). In experiment 1, FM jamming sounds mimicking echolocation pulses of P. abramus were prepared. All bats showed significant increases in the terminal frequency (TF) by an average of 2.1–4.5 kHz when the TF of the jamming sounds was lower than the bats' own pulses. This frequency shift was not observed using jamming frequencies that overlapped with or were higher than the bats' own pulses. These findings suggest that JAR in P. abramusare sensitive to the TF of jamming pulses and that the bats' response pattern was dependent on the slight difference in stimulus frequency. In experiment 2, when bats were repeatedly exposed to a band-limited noise, the bats in flight more frequently emitted pulses during silent periods between jamming sounds. These results demonstrate that bats could rapidly adjust their vocalized frequency and emission timing to avoid frequency and temporal overlap with jamming sound even during flight. [Research supported by JSPS.]
Influence of mouth opening and gape angle on the transmitted signals of big brown bats (Eptesicus fuscus)
Authors: Kloepper Laura N. , Gaudette Jason , Simmons James , Buck John R.
Published: May 2014

The big brown bat (Eptesicus fuscus) produces echolocation sounds in its larynx and emits them through its mouth. The bat is presumed to change the directionality of the emitted echolocation beams by modifying its mouth opening width. We analyzed infrared video sampled at 240 fps synchronized to ultrasonic recordings from a Knowles Electret microphone sampled at 192 kHz. Mouth angles for each emitted echolocation pulse were calculated offline and compared to the pulse's time-frequency characteristics. Our results indicate that the mouth influences both the amplitude and spectral characteristics of the emitted pulse.
Acoustic tracking of bats in clutter environments using microphone arrays
Authors: Matsuo Ikuo , Wheeler Alyssa , Kloepper Laura , Gaudette Jason , Simmons James A.
Published: May 2014

The big brown bat, Eptesicus fuscus, uses echolocation for foraging and orientation. Bats can change the echolocation calls dependent on the environments. Therefore, it is necessary to clarify the changes of acoustic characteristics of these calls. In this study, the flight path of the bat were tracked by computing the time differences of arrivals (TDOA) at the microphone array system in the flight room. The acoustic patterns of echolocation calls could be calculated from the measured call data at each microphone by compensating the spread and absorption loss. The head aim and beam pattern at each harmonics were computed from these acoustic patterns of echolocation calls. It was examined whether these acoustics beam patterns were dependent on clutter environment, that is, density of chains. [This research was supported by ONR, NSF, and JST, CREST.]
Transcranial ultrasound-optical transmission correlation
Authors: Meral Faik C. , Naing Zun Zar Chi , Meyer Felicity A. , Jafferji Mufaddal A. , Power Chanikarn , Clement Greg T. , White Phillip J.
Published: May 2014

Although the transmission of ultrasound (US) through the skull bone has been demonstrated for both therapeutic and imaging applications, the clinical efficacy of certain transcranial US applications remains limited by the highly attenuating properties of skull bone. For those applications, the ability to pre-procedurally determine those areas of the skull that are less attenuating to US could be a tremendous asset for improving the use of US in the brain. To present a possible solution, we have hypothesized that the optical transmission intensity at points across the skull surface can be correlated with the local US transmission efficiency. The demonstration of this correlation would potentially allow for the use of integrated lasers and photodetectors within a HIFU system to create a patient-specific transmission map of the skull. We have statistically investigated the relationship between transmitted optical and US intensities over multiple points across several ex vivo human calvaria to demonstrate this correlation. Along with the results of the analysis, preliminary designs to incorporate optical transmission assessment in transcranial HIFU and echoencephalography will be presented.
Transcranial passive cavitation mapping with a linear array: A simulation study with clinical datasets
Authors: Arvanitis Costas D. , Clement Gregory , McDannold Nathan
Published: May 2014

While numerous investigations that explore the unique properties of acoustic cavitation have recently demonstrated very promising results for a wide range of applications, there is a need to develop new and noninvasive methods that will lead to (1) deeper understandings of the interactions involved, (2) their optimal use for therapy or diagnosis, and (3) ultimately their translation to the clinics. Toward this aim, we developed finite difference time domain (FDTD) simulations to transcranially map and assess the diverging pressure waves generated by oscillating microbubbles. The skull and brain tissue acoustic properties (density, speed of sound, and absorption) were extracted from clinical CT datasets. Point sources derived by microbubble dynamics models were also incorporated and propagated toward a virtual US array that was used to perform passive acoustic mapping (PAM). The FDTD simulations suggest that the microbubbles' pressure waves propagating through the skull lose 97% of their strength as compared to propagation in water. The simulations also indicated that transcranial PAM is possible with an 80 mm aperture linear array; however, at wider apertures (150 mm), significant aberration was introduced. Incorporation of variable speed of sound to the PAM back-projection algorithm corrects the aberrations and significantly improves the resolution.
Drug delivery through the opened blood-brain barrier in mice and non-human primates
Authors: Konofagou Elisa , Chen Cherry , Chen Hong , Downs Matthew , Ferrera Vincent , Olumolade Oluyemi , Samiotaki Gesthimani , Sun Tao , Wang Shutao , Wu Shih-Ying
Published: May 2014

Over five million U.S. men and women suffer from neurodegenerative diseases. Although great progress has been made in recent years toward understanding of these diseases, few effective treatments and no cures are currently available. This is mainly due to the impermeability of the blood-brain barrier (BBB) that allows only 5% of more than 7000 small-molecule drugs available to treat only a tiny fraction of these diseases. Safe and localized opening of the BBB has been proven to present a significant challenge. Focused ultrasound (FUS), in conjunction with microbubbles, remains the sole technique that can induce localized BBB opening noninvasively and regionally. In the past, our group has focused on cavitation monitoring during BBB opening in both mice and non-human primates, assessment of safety and drug efficacy using behavioral testing, delivery of molecules of variant size through the opened BBB, investigation on the role of the microbubble diameter and use of nanodroplets. We will briefly highlight these past findings as well as introduce newer accomplishments such as its role in enhancement of drugs for neuroprotection and neuroregeneration in the treatment of Parkinson's, the use of alternative routes of systemic administration for larger drug dosage, dependence of the BBB opening size on the acoustic pressure, real-time monitoring of the microbubble perfusion of the brain, cavitation prediction of the timeline of BBB opening, and targeted delivery using adeno-associated viruses.
Effects of diffraction on acoustic radiation force produced by sound beams incident on spherical viscoelastic scatterers in tissue
Authors: Treweek Benjamin C. , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: May 2014

The theory for acoustic radiation force on a viscoelastic sphere of arbitrary size in tissue was extended at the spring 2013 ASA meeting to account for nonaxisymmetric fields incident on the scatterer [Ilinskii et al., POMA 19, 045004 (2013)]. The results were presented in a form that permits inclusion of as many spherical harmonics as needed to describe the field structure. At the fall 2013 ASA meeting, it was shown that for spheres having sizes up to about one wavelength, only four or five spherical harmonics are required for convergence of the solution when plane waves are incident on the scatterer. At the present meeting, the model is applied to diffracting sound beams incident on the scatterer. The analysis is based on angular spectrum decomposition of the incident field, expansion of the resulting plane waves in spherical waves, then a Wigner transformation of the latter back into spherical coordinates with polar axis coinciding with the beam axis, and finally integration over solid angle to obtain the spherical wave amplitudes used in the theory. Results are presented for different radiation patterns illustrating dependence of the radiation force both on beamwidth and on wavelength relative to the size of the scatterer.
Reflections of Kim Benjamin as a student, professional colleague, and personal friend
Authors: Stepanishen Peter R.
Published: May 2014

Kim was a very special person who I was privileged to know as a student, professional colleague, and a close personal friend. After completing his undergraduate degree in Physics at URI in 1975, he was accepted into the Masters Program in Ocean Engineering at the University of Rhode Island where I served as his advisor and major professor. While working on an NIH grant to develop two-dimensional planar arrays of ultrasonic transducers for medical diagnostic purposes, Kim developed his lifelong passion for acoustic transducers. Some of his early “experiences with transducers” will be shared in the presentation. During this time period, Kim also investigated and developed the use of FFT methods for the backward projection of acoustic fields from planar sources. His early contributions in this area laid the foundation for much of the subsequent acoustical holographic work by others over the following several decades and will be briefly reviewed. In the 1980s and 1990, it was clear that Kim was becoming a “transducer guru” as evidenced by his research, reports, and related ASA presentations. I will share some recollections of Kim from this period and our many “extended lunches” during the last several years.
Novel, broadband piezocomposite transducers for Navy applications
Authors: Pazol Brian , Mayo Timothy
Published: May 2014

Piezocomposites (a two phased material consisting of piezoceramic and polymer) are a widely known form of piezoelectric material with proven advantages over conventional monolithic piezoelectric ceramics. Transducers made with piezocomposite are naturally broadband, have high sensitivity, can be easily shaded for sidelobe suppression, and can be conformed to a variety of shapes. Materials Systems Inc. (MSI) utilizes a low cost injection molding technique that allows large areas to be made by tiling ceramic preforms into large areas at a reasonable cost. There is a large design space that allows better transducer optimization by adjusting the matrix material, active material, and the ratio of active to inactive material (volume fraction). Kim Benjamin recognized the benefits of piezocomposite early in its development. Over the years, he developed many novel and high performance broadband piezocomposite transducers. This paper presents a brief overview of several unique piezocomposite transducers that he developed with MSI. These includes a Constant Beamwidth Transducer (CBT), torpedo homing arrays, and towed high power sources for a variety of Navy applications. Several of Kim's novel fabrication techniques and measured transducer performance will be presented.
Transducer cloaking for Kim Benjamin
Authors: Butler John L.
Published: May 2014

There is an effort to develop metamaterials for cloaking objects in a way that eliminates backscattering and fills in the shadow zone. The development of this cloaking material for spherical and other shapes would inhibit the acoustic detection of objects, such as mines, torpedoes, UUV's, and, ultimately, submarines by a means which would make them invisible to acoustic waves. It has, however, been pointed out that this form of inactive cloaking could cover a target in a way that shields the target from using its own acoustic sonar means for detecting the source, unless the cloaking could be turned off. We address this issue by presenting an active cloaking transducer system which effectively cloaks the target and yet can also be used as an acoustic sonar system. Equivalent circuits and finite element models are used to demonstrate transducer cloaking. This would have been a good transducer project for Kim Benjamin to implement and I believe he would have enjoyed the challenge and developed one of the best cloaking transducer arrays possible.
Ken Eldred—Mentor
Authors: Potter Richard
Published: May 2014

I met Ken Eldred at Wyle Laboratories in Alabama in 1963 as a young, green engineer shortly after he formed a staff to support NASA's Apollo program. Later, I was joined by other graduates of the Institute for Sound and Vibration Research, Southampton University, England. Ken led us as we undertook exciting and challenging projects. At Wyle, Ken actively mentored us, encouraging us to develop our investigative skills, adapt to new technologies, and write understandable, readable, and useful reports. He encouraged me to produce ideas and he listened to my suggestions, which he carefully reviewed and then, gently, offered corrections and suggested direction. I, and many of us, owe our successful careers to his mentoring. I will describe some particular work and list some who prospered under his leadership. I moved back to England but then, later, returned to the United States and rejoined Ken at Bolt Beranek and Newman in Cambridge. Again he showed interest and encouragement as I expanded my noise work to other aspects of industrial hygiene, later forming my own companies.
The administrative leadership of Harvey Hubbard
Authors: Schmid Charles E.
Published: May 2014

Anyone who met Harvey Hubbard knew right away that he was a gentleman. His unassuming manner belied the long list of his accomplishments from the time he left a one-room school in Franklin County, Vermont to his death at age 90 in Newport News, Virginia, in 2012. His endeavors were both technical and administrative, but only the latter will be covered in this presentation, leaving the technical topics to other speakers. The focus will first be on his presidency of the Acoustical Society of America (1989–90). His leadership in selecting and hiring the Society's first executive director (which directly impacted this author) was carried out with his usual professional graciousness. A number of other innovations which occurred during his presidency will be described, such as the establishment of an Investment Committee, which has become vital to the Society's economic well-being. He held many managerial positions in other non-profits, for-profits, and governmental organizations, which will be mentioned to fully understand the breadth of his managerial contributions. [The author would like to acknowledge Elaine Moran for tracking down much of the information which will be presented.]
Harvey H. Hubbard and his contributions to wind turbine noise (among other things)
Authors: Shepherd Kevin P.
Published: May 2014

Following his long NASA career devoted primarily to the understanding and reduction of aircraft noise, Harvey Hubbard came out of retirement to pursue an interesting opportunity that was presented by issues concerning the sound from large wind turbines. This paper will attempt to summarize this pioneering work on wind turbine noise, along with some other accomplishments and recollections.
Measuring viscoelasticity of soft tissues using shear and guided waves
Authors: Urban Matthew W. , Amador Carolina , Nenadic Ivan Z. , Zhao Heng , Chen Shigao , Greenleaf James F.
Published: May 2014

Elasticity imaging has emerged as a viable clinical tool for assisting in diagnosis of certain diseases such as liver fibrosis and cancer. Many methods have been developed for generating and measuring shear waves in soft tissues. The advantage of using shear waves is that the shear wave velocity is proportional to the mechanical material properties of the tissues under investigation. Soft tissues are inherently viscoelastic and considerable effort has been made to quantify the dispersion, or variation of frequency, of the velocity and attenuation of shear waves. This is accomplished by measuring the shear wave motion and using Fourier-based techniques to extract the shear wave velocity and attenuation. Additional considerations are made in tissues where geometric dispersion is also present such as in the heart. Viscoelastic characterization of the shear viscoelasticity of soft tissues in vivo such as human liver, human kidney, and swine heart will be shown. We will also demonstrate parameterization of the results by using a model-free approach or by fitting the shear wave velocity dispersion to rheological models. The diagnostic value of the viscoelastic parameters will be discussed for each particular application. [This work was supported in part by NIH Grant Nos. DK092255, DK082408, and EB002167.]
Shear wave propagation in worm-like micellar fluids
Authors: Gladden Josh R. , Crim Rachel , Gamble Amanda , Labuda Cecille
Published: May 2014

In viscous Newtonian fluids, support of shear waves are limited to the viscous boundary layer. Non-Newtonian fluids which have shear modulus, however, support shear waves over much longer distances. The restoring force responsible for the shear wave propagation arises from the entanglement of high aspect ratio macromolecules. We report low frequency (30–60 Hz) shear wave studies of aqueous worm-like micellar fluids composed of cetyltrimethylammonium bromide (CTAB) for the surfactant and sodium salicylate (NaSAL) as the salt over a wide concentration range (20–500 mM CTAB). Shear speeds range from 75 to 700 mm/s over this concentration range at room temperature with evidence of two phase transitions at 200 mM and 375 mM CTAB. Shear stress attenuation and temperature resolved measurements between 20 and 40 C will also be presented.
In-situ ultrasonic evaluation of structural/nuclear materials
Authors: Sakthipandi K. , Rajendran V.
Published: May 2014

Physical properties of components through ultrasonic non-destructive evaluation play a vital role to understand in quality and strength materials and also help to extend life of the components. Measurements of ultrasonic velocity and attenuation as a function of temperature were used to reveal the structural/phase transitions, initiation and growth of fatigue-induced damages, and life-limiting fatigue crack during the aging of materials. Indigenously designed experimental set-ups was designed for in-situ ultrasonic velocities and attenuation measurement over a wide range of temperature from 120 to 300 K and 300 to 1200 K. The ultrasonic velocity/attenuation measurements carried out on AISI316 stainless steel, β-quenched zircaloy-2 specimen and maraging steel were used to explore the formation and resolution/recrystallization of intermetallic and coherent precipitations. Further, the ultrasonic velocity/attenuation measurements carried out in bulk and nano perovskites samples (La1xSrxMnO3, Nd1xSrxMnO3, Sm1xSrxMnO3 and Pr1xSrxMnO3) were used to explore the phase transition (TC), charge ordering (TCO), and Jahn-Teller (TJT) temperature. The bulk and nanocrystalline nature of the perovskites were explained based on observed anomalies at transition temperature. The plot of first derivative of temperature dependent ultrasonic parameters was used to reveal the precise information to detect the early stages of microstructural and substructure variations in material.
Physical constraints on lossy acoustic metamaterials with complex effective properties
Authors: Sieck Caleb F. , Haberman Michael R. , Alù Andrea
Published: May 2014

Recent theoretical and experimental work on acoustic metamaterials (AMM) has demonstrated materials that demonstrate many properties, such as negative modulus and density, beyond what is capable using conventional materials. In most cases, AMM are assumed to be passive and causal with frequency dependent losses accounted for via complex modulus and density. Despite the maturity of AMM research, literature concerning the physical constraints on the complex effective constitutive properties for passive, causal AMM is very limited. This work presents the physical limits for the real and imaginary effective dynamic mass density and dynamic compressibility via recourse to restrictions placed on the AMM by conservation of energy, passivity, and causality. We further note that constitutive properties are determined from the effective wavenumber and impedance extracted from simulation or experiment. Although care is normally taken to guarantee that passivity holds for the wavenumber and impedance, assumptions implicit in various homogenization schemes can result in constitutive properties that do not satisfy passivity and causality. This work will therefore also discuss implications on AMM homogenization and extraction of properties due to constraints based on the foundational concepts of conservation of energy, passivity, and causality. [This work was supported by the Office of Naval Research.]
Gradient perception of within-category nasality in English vowels
Authors: Zellou Georgia , Dahan Delphine
Published: May 2014

Nasality encodes a phonemic consonant contrast in English, and its acoustic correlates affect adjacent vowels. The phonological status of nasality predicts that people encode vowel nasality as a discrete and binary feature, i.e., as the presence or absence of velum lowering. The present study examined whether listeners can also infer the degree of velum lowering encoded in a vowel. We resynthesized 20 word pairs that contrasted in vowel nasality only (e.g., bet vs. bent [produced with no nasal murmur]) and created, for each pair, a continuum of seven stimuli varying linearly in their degree of vowel nasality. The 140 stimuli were used to assess listeners' categorization and discrimination. First, participants categorized each stimulus as oral or nasal. They were then presented with two stimuli selected from the same continuum and judged whether they consisted of physically identical or different tokens. Using linear-regression modeling, we demonstrated that discriminating between two stimuli is determined by their acoustic distance in velum height above and beyond their category assignment. Thus, people can encode velum height in stimuli they categorize identically. This finding adds to the growing body of evidence that listeners track properties of speech that go beyond establishing lexical contrasts.
Gradient coding of voice onset time in posterior temporal cortex
Authors: Anderson Nathaniel D. , Toscano Joseph C. , Fabiani Monica , Gratton Gabriele , Garnsey Susan M.
Published: May 2014

The issue of whether early stages of speech processing are influenced by category has been central to work in speech perception for decades. We present the results of an experiment using fast diffusive optical neuroimaging (Gratton and Fabiani, 2001, Int. J. Psychophysiol.) to address this question directly by measuring neural responses to speech with high temporo-spatial resolution. We found that changes in voice onset time (VOT) along a /b/-/p/ continuum evoked linear changes in neural responses in posterior superior temporal gyrus (pSTG) 100 ms after stimulus onset. This is the first non-invasive observation of such responses in humans. It is consistent with results from recent event-related potential (Toscano et al., 2010, Psychol. Sci.) and fMRI (Blumstein et al., 2005, J. Cognit. Neurosci.) studies, and provides evidence that those results reflect listeners' early encoding of speech sounds in pSTG, independently of phonological categories. Thus, the results provide evidence that speech perception is based on continuous cues rather than discrete categories. We discuss these results in light of recent intra-cranial EEG studies reporting either categorical effects in pSTG (Chang et al., 2010, Nature Neurosci.) or evidence that pSTG maintains fine-grained detail in the signal (Pasley et al., 2012, PLoS Biol.).
Unpredictable and unintelligible: Individual differences in predictability-based reduction affect speech intelligibility
Authors: Turnbull Rory
Published: May 2014

Words spoken in high predictability (HP) contexts tend to be phonetically reduced and less intelligible than words spoken in lower predictability (LP) contexts. However, individual differences in degree and strategies of reduction, and their effects on intelligibility, are largely unexplored. This study examined the role of autistic traits in speech intelligibility. Sixteen participants completed a speech in noise word identification task at 2dB SNR. Stimuli were recordings of words spoken in HP and LP contexts, extracted from sentences produced by talkers ranging in autism-spectrum quotient (AQ) scores. After the identification task, listeners also completed the AQ questionnaire. A higher AQ score indicates a greater prevalence of autistic traits in one's cognitive style. Logistic mixed effect regression modeling revealed an expected effect of duration, such that longer words were more likely to be correctly identified. Further, talkers with higher AQ scores were less intelligible than talkers with lower AQ scores. Unexpectedly, no effect of predictability condition was observed: LP words were not consistently more intelligible than HP words. No effect of individual differences in listener AQ scores was observed. These results suggest that predictability-based enhancement and reduction strategies vary between individuals and are not necessarily for the benefit of the listener.
Multidimensional scaling and order asymmetry of the acoustic change complex to voiceless fricatives in Polish, English, and Finnish listeners
Authors: Brint Emma , Iverson Paul , Wagner Anita
Published: May 2014

The acoustic change complex (ACC) is a P1-N1-P2 onset response to changes between sounds measured using EEG, which when measured at a central location, is not thought to be affected by the language experience of the listener. Recent research has shown that with a pair of stimuli, there is an asymmetry between the ACC recorded when they are presented in one order compared to the other. This study used eight voiceless fricatives to measure the ACC to all possible pairs from EEG recordings of 15 English, Finnish, and Polish listeners. The ACC magnitude was used to perform multidimensional scaling to create a two dimensional perceptual space for each language that is driven by the spectral characteristics of the stimuli. Asymmetry occurred in all three languages depending on how peaky the first and second stimuli were. This asymmetry effect was greater for the Polish group, indicating that the Polish listeners' language experience increases their sensitivity to the spectral peakiness of fricatives. These results show that the ACC is in fact susceptible to native language effects, enhancing its application as a test for auditory speech processing.
Speech intelligibility can improve rapidly during exposure to a novel acoustic environment
Authors: Aspeslagh Sofie , Clark D. Fraser , Akeroyd Michael A. , Brimijoin W. Owen
Published: May 2014

In natural listening environments, the background noises and the acoustic spaces they occupy can vary greatly, both in their characteristics and in their impact on speech intelligibility. It has been suggested that listeners build up a statistical representation of ongoing noises; however, listeners can move around a room or move from one room to another, constantly changing both the background noises and the reverberation around them. If listeners are to make use of such statistics to aid in speech intelligibility, they must engage in a constant adaptation. We asked normal and hearing-impaired listeners to identify in real-time a stream of random target words in a contiguous series of novel acoustic environments lasting 13 s each, thus measuring the extent and time-course of changes in speech intelligibility that listeners experience in a new environment. The results from our task demonstrate that most listeners experience a rapid increase in speech intelligibility over several seconds of exposure to certain acoustic environments, but not to others. This suggests that there are classes or types of noises and reverberations that can be adapted to over a short time course and others that cannot. [Work supported by the MRC and the CSO.]
Effects of perceptual anchors on nasality ratings in speech
Authors: Galek Kristine E. , Watterson Thomas
Published: May 2014

To study the effects of perceptual anchors on nasality ratings in speech. Speech samples were obtained from 95 hypernasal children and 5 normal controls. Samples were randomized and duplicated (6 sets of 100 samples). Six listening groups (N = 129) rated nasality on a seven-point scale (“1” normal nasality to “7” severe hypernasality). Anchors were located at different points along the continuum for each group. A single anchor located at scale value “4” or at scale values “3” and “5” educed an assimilation of ratings. Anchors placed at scale values “1” and “7” educed a contrast effect in that the distribution of ratings shifted away from the anchor sites. A single anchor placed at scale value “7” educed a systematic regression of the distribution of ratings away from the anchor site. Three anchors placed at scale values “1”, “4” and “7” educed a more even distribution of ratings across the entire scale than the other five anchored conditions. Three of the five anchor groups consistently rated the first sample of the rating task a scale value “2” (based on median findings) even though the first sample was a normal control sample. The degree of nasality in speech is influenced by perceptual anchors.
Locus of phonological deficits in adults with dyslexia
Authors: Del Tufo Stephanie N. , Noyes Joslynn , Sylvia Rebecca , Montanaro Sarah , Theodore Rachel M.
Published: May 2014

Dyslexia is a developmental disorder that has traditionally been viewed as the consequence of impaired phonology. However, recent evidence suggests that the phonological deficits observed in dyslexia may reflect phonetic impairment earlier in the processing stream. The goal of the current work is to test this hypothesis. We use a phoneme-monitoring task to evaluate the relative use of two sources of information for making phonemic decisions (e.g., deciding if “dog” begins with /b/ or /d/). One source comes from a prelexical analysis of the speech signal (phonetic information) and the other source comes from a postlexical analysis (phonological information). Research has shown that healthy listeners flexibly shift between these sources based on experience with the acoustic signal. Specifically, phonemic decisions for native speech reflect phonetic information whereas phonemic decisions for foreign-accented speech reflect the use of phonological information. The interpretation is that phonetic processing is difficult for the foreign-accented speech, leading to a greater reliance on a postlexical analysis. If adults with dyslexia have impairment in phonetic processing, then we predict that phonemic decisions will reflect the use of phonological information for both types of speech, suggesting that the native speech signal is being processed as if it were accented.
Auditory and phonetic contributions to the neural mechanisms underlying vowel perception
Authors: Burnison Jeremy , Brumberg Jonathan
Published: May 2014

One aspect of speech perception is our ability to identify the vowel sounds of spoken language. Identification accuracy of acoustic vowel targets has been shown to decrease as the first two formant frequencies of target sounds become more similar, suggesting that a vowel discretization exists in the F1-F2 auditory perceptual space. This is supported by prior work showing neural processes during vowel perception reflect recognition of discrete phonemes. In this study, we investigated the differential contributions of phonetic and acoustic factors on vowel perception using an event-related potential (ERP) protocol. Subjects first identified synthesized acoustic presentations of American English monopthong vowel sounds by selecting one of eight representative hVd words. Next, we presented synthesized sounds along the trajectory between two neighboring vowels in a mismatched negativity (MMN) oddball paradigm with one exemplar vowel as the standard stimulus. Preliminary results show statistically significant MMN amplitudes attenuate with standard-deviant vowel similarity, but include an additional MMN amplitude reduction at 50% vowel identification accuracy based on the behavioral responses. These results further clarify the neurological processing of vowel perception as a combination of auditory and phonetic factors in which acoustic differences elicit graded MMN responses that are augmented by shifts across phonetic boundaries.
Consonant confusability and its relation to phonological similarity
Authors: Khan Sameer ud Dowla
Published: May 2014

Gradient similarity avoidance patterns in Bengali echo reduplication suggest that the most similar consonants to /t/ are, in order, /t, th, d, t, s, th, k, .../. Converted to confusability, this ranking predicts that aspiration is most confusable, followed by voicing, minor place, continuancy, major place, and sonority. To confirm this, 24 native speakers identified syllables masked with babble, noise, or nothing (“clear”). Results indicate that confusability reflects similarity as predicted by avoidance patterns. In clear speech, most errors involved voicing and aspiration. Other errors reflected dialect-specific alternations. Noise introduced the percept of a loud burst: fricatives were often heard as affricates, non-alveolar coronals as alveolars, and non-coronals as coronals. Babble largely resembled noise. This pattern suggests that voicing is the most confusable feature, followed by aspiration, minor place and continuancy, major place, and lastly sonority. This ranking seems Bengali-specific, as studies of English find place to be significantly more confusable than manner and voicing. These results suggest that at least for Bengali, phonological alternations and perceptual confusability are argued to be better representations of how speakers judge similarity, rather than patterns in the lexicon or metrics such as shared natural classes metric of Frisch et al. (2004).
Information structure guides prominence perception
Authors: Bishop Jason
Published: May 2014

The present study investigates the effect of information structure on the perception of prosodic prominence in English. In particular, we probed for top-down effects related to the size of the focus constituent (broad VP focus versus narrow object focus) in simple subject-verb-object sentences using a naïve prosody “transcription” task. In this task, listeners heard the same productions of a sentence, but in different information structural (i.e., question) contexts, and provided self-report decisions about the prominence of words using a Likert scale. Two primary questions were asked. First, does information structural interpretation produce expectation-based prominence perception? In this case, it was predicted that the presence of focus would induce perceived prominence independent of the signal (via expectations based on experience with production patterns). Second, does information structural interpretation modulate signal-based prominence perception? In this case, it was predicted that the presence of focus would enhance sensitivity to signal-based cues (via the modulation of attentional resources). Results are presented that show evidence for both types of effects, demonstrating a multifaceted influence of sentence-level semantic/pragmatic meaning on the perception of the signal.
Laboratory measurements of compressional and shear wave speed and attenuation in muddy sediments
Authors: Ballard Megan S. , Lee Kevin M. , Muir Thomas G.
Published: May 2014

As demonstrated by William M. Carey's field measurements in Dodge Pond, muddy sediments are characterized by a slow compressional wave speed and a low compressional wave attenuation [Carey and Pierce, POMA (5), 7001, 2009]. To gain insight into the measured data, a theoretical treatment of muddy sediments, named the Card House theory [Pierce and Carey, POMA (5), 7002, 2009], was developed. According the theory, isomorphous substitution causes each mud platelet to carry a net negative charge, and the resulting electrical interaction between platelets is responsible for creating a card-house structure. In this work, we examine laboratory measurements of compressional and shear wave properties in mud. Compared to the Dodge Pond measurements, which were affected by the size and distribution of gas bubbles present in the mud, the volume of gas in the laboratory samples was reduced by applying a vacuum. The estimated compressional wave speed is consistent with predicted values for a relatively gas-free mud. The estimated shear wave speed compares favorably with predicted values from the Card House theory. The electrochemical basis of the Card House model and its acoustical implications are also investigated. [Work supported by ARL:UT IR&D.]
Bill Carey and sound attenuation in marine sediments
Authors: Chapman Ross
Published: May 2014

Experiments carried out by Bill Carey in the Hudson Canyon off the New Jersey coast provided a great wealth of data for the study of low frequency sound propagation in shallow water. His analysis of the transmission loss data, reported in a series of papers dating from the mid 1990s, indicated a non linear frequency dependence of sound attenuation in the sediment material. This work provided a large base of experimental evidence for the non linear dispersion predicted by the Biot theory of sound propagation in porous media, and it stimulated new studies on sound propagation in marine sediments by many researchers, including Bill Carey himself. This paper reviews the results obtained by Carey from the Hudson Canyon experiments and places them in the context of new results from more recent experiments using different techniques and observables. Analysis of results from the new work indicates that Carey's observation of non linear frequency dependence in sediment material in the Hudson Canyon applies to attenuation of sound in different types of marine sediments.
In memory of Bill Carey
Authors: Clark Cathy Ann
Published: May 2014

Bill Carey has been a strong and influential mentor to many young and not-so-young acousticians and engineers. He had a profound effect on my career, encouraging me to publish my work and to attend Acoustical Society Meetings. His work in bottom acoustics, noise directionality, and surface effects, in particular, provided significant input to my research. He was also instrumental in nominating me for Fellowship in the Acoustical Society. I am deeply grateful and appreciate having an opportunity to remember him in this session.
Measuring speech intelligibility using impulse responses: Impact of the decay range on the speech transmission index
Authors: Hak Constant , Wenmaekers Remy
Published: May 2014

IEC 60268-16 describes how to measure the Speech Intelligibility Index STI and its simplified derivatives such as STITEL and STIPA, using two measurement techniques. The first and oldest technique is based on a set of modulated noise signals used as a stimulus. The second method uses impulse responses obtained from maximum length sequence (MLS) or swept sine stimuli, deconvolution and Schroeder's Modulation Transfer Function (MTF). This technique is gaining more and more ground through advancing technology. The ability to modify the background noise component of a measured impulse response is one of the advantages of this technique, but requires a certain minimum impulse response quality. A measure of the quality of an impulse response is its decay range. The influence of the impulse response decay range on the calculated STI value is investigated. As in a previous study on the ISO 3382-1 parameters, this is done by using the Impulse response to Noise Ratio INR as an estimator for the decay range. The result is a proposal for the minimum required decay range to accurately measure the STI, based on the Just Noticeable Difference JND and the INR.
Geographic variation in acoustic signals of freshwater fishes
Authors: Johnston Carol , Phillips Catherine , Noel Patty
Published: May 2014

Although well studied in other taxa, geographic variation in signal structure has been poorly studied in fishes. Signal divergence in marine fishes depends on larval form; pelagic larvae disperse more widely than demersal forms, limiting opportunities for isolation and subsequent divergence. Freshwater fishes, especially those restricted to headwater habitat, are isolated by drainage. There are many examples of species radiations in groups of North American freshwater fishes within drainage networks, including darters, minnows, and catfishes, some of which are restricted to single streams. Our data demonstrate divergence of acoustic signals among populations of stream and riverine fishes at multiple scales, and often in the absence of apparent morphological variation. Two model species, Longear Sunfish and Whitetail Shiner, differed in the temporal components of calls, while darter and sturgeon models showed variation in both temporal and spectral call components. In the case of the sturgeon, the populations were genetically distinct. Furthermore, data for Whitetail Shiner suggest that calls associated with courtship were strongly associated with geographic isolation, while divergence in those characteristics associated with aggression may be driven by genetic drift. We suggest that variation in acoustic signal structure may be common in freshwater fishes and discuss implications for mate choice.
Population structure of humpback whales in the western and central South Pacific Ocean determined by vocal cultural exchange
Authors: Garland Ellen C. , Noad Michael J. , Goldizen Anne W. , Lilley Matthew S. , Rekdahl Melinda L. , Garrigue Claire , Constantine Rochelle , Daeschler Hauser Nan , Poole M. Michael , Robbins Jooke
Published: May 2014

Male humpback whales (Megaptera novaeangliae) produce a continually evolving vocal sexual display, or “song,” which is shared by all males within a population. The rapid cultural transmission of this display between distinct but interconnected populations within the western and central South Pacific region presents a unique opportunity to investigate population connectivity based on a vocal display. Quantitative analyses were conducted on eleven years of data to investigate vocal groupings based on song types shared between populations, to produce an acoustically derived population structure for the region. Four distinct vocal groupings resulted; the western group contained a single population, off eastern Australia, the central group was comprised of whales around New Caledonia, Tonga and American Samoa, and finally the whales of the eastern region were split into two groups, one around the Cook Islands and the other in the waters of French Polynesia. These groupings broadly agree with results obtained using genetic and photo-identification methods, and confirm that humpback whales are likely to form separate breeding populations rather than panmictic subpopulations. This study demonstrates the utility of using culturally transmitted vocal patterns as a way of defining populations, at least in this species.
Ultrasound communication for body senor network
Authors: Li Meina , Hyoung Canghee , Hwang Junghwan , Kang Sungweon , Park Kyunghwan
Published: May 2014

Radio frequency (RF) waves have been the dominant part in the field of wireless communication. However, RF waves has the limitation when transmit through the human due to the most of body composition is water. Therefore, the ultrasound that has good propagation in the water has been proposed as the new communication wave for the body sensor network (BSN). Two ultrasonic sensors are used in the communication system. One was placed under skin as the transmitter (Tx) and the other one as the receiver (Rx) was placed right toward the Tx on the top of skin. The Tx can detect and monitor the physiological signal inside of body then transmit the information to the Rx. After the Rx received the signal, it can transmit the information to the doctor also can release the drug to the patient. The modulation of ultrasonic wave has been experimented by three common modulation ASK, PSK, FSK for digital communication. The results showed the ultrasound wave is a possible communication method for body sensor network.