bluuebunny/crossref_metadata_2025 huggingface dataset:
Free-ranging finless porpoises acoustically inspect their frontal area in advance
Authors: Akamatsu Tomonari , Wang Ding , Wang Kexiong , Naito Yasuhiko
Published: September 2013

Echolocation events, interpulse intervals, and swimming speeds of nine free-ranging finless porpoises in an oxbow of the Yangtze River, China were recorded by datalogger systems attached on the animals. Over 120 h of successful recording indicated that the finless porpoises acoustically inspected their frontal area in advance before swimming silently. The acoustical sensing distance estimated by the interpulse interval was significantly larger than the swimming distance without echolocation beforehand. Terminal phase which was already known in the echolocation behavior of bats could be found in free-ranging finless porpoises. The terminal phase is the decreasing interpulse intervals in an echolocation pulse train that are observed just before the prey capture. During the terminal phase of finless porpoises, linearly decreased interpulse intervals were recognized. In the mean time, the swimming distance and the change of the sensing distance were closely correlated with each other. This suggests that the finless porpoise knew precisely the distance to the approaching target in the time scale of subsecond order. Acoustical sensing effort was considered to be controlled appropriately by free-ranging finless porpoises to obtain underwater information they need. [Research supported by Promotion of Basic Research Activities for Innovative Biosciences, Bio-oriented Technology Research Advancement Institution, Japan.]
Influence of ambient noise on the use of sound by marine animals
Authors: Cato Douglas H.
Published: September 2013

Ambient noise provides the basic limitation on the use of sound by animals since signals of interest must be detected against the noise. In the ocean, ambient noise is very variable, both temporally and spatially. Temporal variation is more than 30 dB, with 20 dB being common and occurring over time scales of order 1 day, causing substantial variation in audible distances of sources (order a factor of 10). This paper examines how ambient noise affects the use of sound by animals and how it may have shaped aspects in development acoustic function. It draws on a large amount of data from the Australian region which is relatively free of anthropogenic noise, and contains a wide range of biological activity. Characteristics of ambient noise are compared with those of some marine animal vocalizations to assess whether these have any optimization against the noise. Although low acoustic absorption loss in water provides the potential for sound to be used over large distances, the variability of ambient noise and propagation suggests that high source levels of marine animals are needed to allow efficient use of sound over moderate distances most of the time, rather than large distances under exceptional conditions.
A tribute to Van Holliday: Completing the circle from plankton to whales
Authors: Cummings William C.
Published: September 2013

After the Bachelor’s and Master’s degrees from the University of Texas and a Doctorate from the University of California, San Diego, Van Holliday hit the water with both feet moving as fast as possible, nary sinking a bit to this day. From the outset he has been a leader and innovator in methods of high-frequency sonar to identify and assess individual animals, populations, and biomasses from zooplankton to adult fishes. Although we’ll revisit some of those highlights, my 35-year association with this distinguished scientist also included an opportunity to share comparatively little known acoustics research at the highest marine trophic level, the pinnipeds and whales. Van’s scientific endeavors, together with extremely talented colleagues, remain tireless yet somehow he always finds wherewithal to unselfishly help others as testimony to the adage that whenever help is needed one had best seek out their busiest acquaintance. In recognition of his contributions to basic and applied marine science, the U.S. Navy recently bestowed upon Van its highest award for Science and Technology. It will be a pleasure and honor to tell you more of this valued friend and colleague, because you will never hear about it from the scientist, mentor, and gentleman himself.
Vertical array measurements of humpback whale songs
Authors: Au Whitlow W. L. , Lammers Marc O. , Pack Adam A. , Herman Louis
Published: September 2013

The songs of eight male humpback whales were recorded at ranges varying from 20 to 40 m with a vertical array of hydrophones that had a flat frequency response to 24 kHz. The songs consisted of bursts of sounds called units. Units were organized into phrases and phrases into themes. Most of the units had mean duration between 1 and 2 s and mean silent periods between units between 1 and 2 s. Many of the recorded songs contained units that had high-frequency harmonics that extended beyond 22 kHz. These harmonic results suggest that humpback whale songs have a broadband quality not previously reported and may provide some insights on the high-frequency limit of hearing in these whales. The source levels of the songs were also estimated by considering the root-mean-square sound-pressure level referenced to 1 m for the unit with the largest level for different phrase within a song. Source levels varied between 171 to 189 dB re: 1 μPa. Singing escorts have been regularly observed within two whale lengths of females and these observations and knowledge of source levels provide estimates of sound-pressure levels that male humpback whales expose female whales to.
Light and lunar cycle as cues to diel migration of a sound-scattering layer
Authors: Benoit-Bird Kelly J. , Au Whitlow W. L.
Published: September 2013

The Hawaiian mesopelagic boundary community is an island-associated midwater scattering layer comprised of small fishes, shrimps, and squids that undergoes diel vertical as well as horizontal migrations. It has been hypothesized that light levels are an important cue or trigger for vertical migration and presumably, horizontal migration. The migration pattern of the scattering layer was measured over complete lunar cycles while the incident light levels were recorded. Due to differences in the rise and set times of the moon and cloud cover, light and lunar cycle were not completely coupled, allowing separation of the light effects of moon phase and other cues associated with lunar cycle. Four calibrated echosounder moorings were deployed with approximately even spacing, perpendicular to the leeward coast of Oahu. Moorings were deployed for one complete lunar cycle at each of three locations, recording 10 echoes every 15 min. Light sensors measured the nocturnal light intensity at 30-s intervals. Statistical analysis revealed significant effects of both light and other lunar cycle cues. Overall, the effect size was very low considering the light transmission characteristics of the subtropical Pacific, making measurement from stationary acoustic platforms critical.
Bioacoustics and D. V. Holliday: A scientific tribute
Authors: Foote Kenneth G.
Published: September 2013

A number of Holliday’s seminal contributions to the acoustics of observing aquatic organisms are noted. Schooling pelagic fish have been sized from their echo resonance structure; fish swimming speeds have been measured through the Doppler effect; and snappers/groupers have been enumerated by high-resolution sidescan sonar. Zooplankton have been sized through multiple-frequency measurements of backscatter, and related to the underlying oceanography. Bowhead whales have been localized and tracked by means of a passive sonobuoy array. Certain themes have recurred, emphasizing the importance of both frequency diversity and spatial resolution in quantitative applications. Devices have been designed and built to solve specific problems, advancing the state of the art in these areas. For the student, the respective published work exemplifies the scientific method, introducing an important observational problem, describing its systematic approach, and interpreting results by means of simple but sound physical models. [Work supported by ONR.]
Measurements of the stability of the effective apodization for the nonlinearly generated second harmonic as a function of propagation distance
Authors: Fedewa Russell , Wallace Kirk , Holland Mark , Jago James , Ng Gary , Rielly Matthew , Robinson Brent , Miller James
Published: September 2013

The concept of an effective apodization was introduced to approximate the nonlinearly generated second harmonic field pattern based solely on the linear propagation of a field transmitted at the frequency of the harmonic. We have previously demonstrated that transmitting with an effective apodization determined from measurements made only in the focal plane yields an accurate description of the nonlinearly generated field over a very wide range of depths. The goal of this work was to determine the stability of the effective apodizations obtained from measurements of the ultrasonic field in a series of planes before and beyond the focal zone. Transverse 2D scans of the transmitted fields were performed with a 0.6-mm-diam. hydrophone for both vascular and cardiac arrays. Linear angular spectrum backpropagation of the measured fields determined the effective apodizations. These measurements were compared with simulations based on a nonlinear Burgers equation enhanced angular spectrum approach. The resulting effective apodizations of the second harmonic field were remarkably constant (differing by typically a few percent and never by more than 9.4% from the mean) for ten axial positions ranging from 0.1 to 1.6 times the focal distance. [Work supported by NIH HL072761 and Philips Medical Systems.]
Flow measurements based on speckle decorrelation: Simulation and experiment
Authors: Kripfgans Oliver D. , Zhu Juan , Rubin Jonathan M. , Fowlkes J. Brian , Hall Anne L.
Published: September 2013

Traditional Doppler-based flow measurements suffer from bad signal to noise for large angles between the wavevector and the flow direction. To overcome this limitation, speckle decorrelation might be used to measure lateral flow. Experiments were performed on a flow phantom (tube diameter 6.35 mm, flow 1.6 mL/min) with the tube axis positioned in the imaging plane of a GE Logiq 9 scanner. IQ data sets of ten frames with 16 firings per scanline were recorded and speckle decorrelation used to estimate flow speeds throughout the image. The decorrelation computations were performed over different kernel types and compared to simulations performed using Field II by J. Jensen with acoustical transmit as well as beamforming parameters set to match experiments. Speckle decorrelation rates in experiments scale correctly for the parabolic flow profile inside the tube. Simulations reproduced a similar but smoother profile. Flow velocities could be estimated using a scaling factor based on the spatial correlation of the beam. The combination of velocity estimates from Doppler and speckle decorrelation may provide a more uniform display of flow and lead to less angle dependence. [Research supported by U.S. Army Grant No. DAMD17-00-1-0344 and GE Medical Systems.]
Numerical evaluation of the omnidirectional behavior of regular polyhedron loudspeakers
Authors: Smith Heather , Leishman Timothy
Published: September 2013

A regular polyhedron loudspeaker (RPL) consists of a rigid enclosure in the shape of a regular polyhedron with loudspeaker drivers mounted within each face. Room acoustics measurements often incorporate dodecahedron loudspeakers presumably as omnidirectional sources of sound. This research is intended to support experimental work to determine which of the five regular polyhedron loudspeaker configurations actually produces the most omnidirectional field over a wide frequency range. Loudspeaker models based on the boundary element method were created to assess frequency-dependent radiation patterns. These models assume that the loudspeaker drivers radiate as plane circular pistons. Far-field sound pressures were generated for several field points around the models (5-deg polar and azimuthal angle increments). Results are presented as directivity balloon plots and compared with experimental measurements. Other numerical results are shown as variations on the experimental setup. These involve dimensional scaling of an entire loudspeaker and dimensional scaling of driver diameters while keeping enclosure dimensions constant. They also involve generation of data at more closely spaced field points (1-deg polar and azimuthal angle increments). Results from a spherical enclosure with radiating pistons centered on the angular coordinates of dodecahedron facial centers are also compared to those produced by a dodecahedron loudspeaker model.
Volume displacement sensors for vibrating beams: Numerical approach
Authors: Jangiti Sai Prassad , Zahui Marcellin
Published: September 2013

The development of volume displacement sensors for vibrating beams is revisited with emphasis on numerical approach. This development supports the implementation of noise control techniques that are based on minimization of volume displacements, velocities, or accelerations of a vibrating structure. This paper first reviews some of the existing general methodologies for the development of volume displacement sensors for vibrating beams using PolyVinyliDene Fluoride (PVDF). The presentation includes the quadratic and modal development of volume displacement sensors for vibrating beams. These techniques are extended to numerical analysis by discretizing the beam and assuming constant sensor shape on each beam element. The result is a system of linear equations in which the assumed constant shapes are the unknowns. The size of the system of equations, which determines the accuracy of the sensor, is directly related to the highest frequency in the signal to be processed. The resulting sensors are numerically and experimentally verified for a simply supported beam. The results show for low-frequency application, relatively simpler sensor shapes can be utilized, whereas for higher frequencies the sensor shape converges to quadratic function. Finally, sensor accuracy and the range of the application frequency are discussed and some sample shapes presented.
Optical measurement of acoustic streaming in a waveguide
Authors: Biwa Tetsushi , Thompson Michael W. , Atchley Anthony A.
Published: September 2013

The generation of time-averaged fluid velocities by acoustic waves is known as acoustic streaming. The recent development of traveling-wave thermoacoustic engines has accelerated the need for a deeper understanding of acoustic streaming. In these devices, mass flow associated with traveling-wave streaming results in a large heat leak. However, no quantitative measurements of traveling-wave streaming have been found in the literature. In the present work, we study acoustic streaming induced by traveling- and standing-wave fields in a cylindrical waveguide. Drivers attached to each end of the waveguide are driven at the same frequency. By tuning the relative magnitudes and phases of the voltages supplied to these drivers, both traveling- and standing-wave fields can be generated. Laser Doppler anemometry has been used to make quantitative measurements of acoustic streaming induced by a standing wave in a resonator [M. W. Thompson and A. A. Atchley, in Nonlinear Acoustics at the Beginning of the 21st Century, edited by O. V. Rudenko and O. A. Sapozhnikov (Moscow, 2002), Vol. 1, pp. 183–190]. We apply this experimental technique to the traveling-wave field in this waveguide, and compare the local acoustic variables and the streaming.
Development of the sound localization cues in cats
Authors: Tollin Daniel J.
Published: September 2013

Cats are a common model for developmental studies of the psychophysical and physiological mechanisms of sound localization. Yet, there are few studies on the development of the acoustical cues to location in cats. The magnitude of the three main cues, interaural differences in time (ITDs) and level (ILDs), and monaural spectral shape cues, vary with location in adults. However, the increasing interaural distance associated with a growing head and pinnae during development will result in cues that change continuously until maturation is complete. Here, we report measurements, in cats aged 1 week to adulthood, of the physical dimensions of the head and pinnae and the localization cues, computed from measurements of directional transfer functions. At 1 week, ILD depended little on azimuth for frequencies <6–7 kHz, maximum ITD was 175 μs, and for sources varying in elevation, a prominent spectral notch was located at higher frequencies than in the older cats. As cats develop, the spectral cues and the frequencies at which ILDs become substantial (>10 dB) shift to lower frequencies, and the maximum ITD increases to nearly 370 μs. Changes in the cues are correlated with the increasing size of the head and pinnae. [Work supported by NIDCD DC05122.]
Reciprocity in the wave reflection and transmission problem
Authors: Bobrovnitskii Yuri I.
Published: September 2013

Matrices of reflection and transmission coefficients of plane waves in media or normal waves in waveguides are, in general case, not symmetric. When all the waves are of the propagating type, the matrix can be symmetrized by normalizing the wave amplitudes with the wave power flow. For evanescent (inhomogeneous) waves this is not valid because of their zero power flow. This difficulty is overcome in the present paper. The main result is that a reflection and transmission matrix becomes symmetric if the wave amplitudes are normalized with the certain energy-like quantity that coincides with the power flow in the case of propagating waves. The result is valid for all types of waves (including those with complex wave numbers) and for all media and waveguides where the classical reciprocity theorem is valid. All symmetry relations, known in the literature for reflection and transmission coefficients follow from the result as particular cases. The result is useful in analysis of multimodal sound fields in composite media. It is illustrated in examples with inhomogeneous waves in fluids and solid waveguides.
Voiceless stop duration under narrow focus and in clear speech
Authors: Ortiz Jeanette A. , Bradlow Ann R. , Pierrehumbert Janet B.
Published: September 2013

Talkers typically hyperarticulate when producing individual speech segments under conditions of sentence-level, or narrow focus and of clear speech, which is speech produced in response to known speech perception difficulties on the part of the listener. This study investigated whether narrow focus and clear speech elicit similar changes in the speech signal. A comparison was conducted between the effects of these two phenomena on the durations of voiceless stops /k/ and /t/ in word-initial and word-medial positions of trochaic, disyllabic words. Both narrow focus and clear speech yielded longer closure and aspiration durations when /k/ and /t/ were in word-initial position. For word-medial stops, narrow focus yielded no change in closure duration and a lengthening of aspiration duration for both /k/ and /t/. In contrast, clear speech yielded no change (/t/) or an increase (/k/) in closure duration, and, more interestingly, significant decreases in aspiration duration for both /k/ and /t/. The different effects of narrow focus and clear speech on voiceless stop production suggest that the local hyperarticulation of sentence-level focus and the global hyperarticulation of clear speech probably do not arise from the same underlying organizational structures.
Rosa’s roses: Reduced vowels in American English
Authors: Flemming Edward
Published: September 2013

Beginning phonetics students are taught that American English has two contrasting reduced vowels, transcribed as [ə] and [ī], illustrated by the unstressed vowels in the minimal pair Rosa’s versus roses. However, little seems to be known about the precise nature or distribution of these vowels. This study explores these questions through acoustic analysis of reduced vowels in the speech of 12 American English speakers. The results show that there is a fundamental distinction between the mid central [ə] vowel that can occur in unstressed word-final position (e.g., in Rosa), and high reduced vowels that occur in most other unstressed positions, and might be transcribed as [ī]. The contrast between pairs like Rosa’s and roses derives from this difference because the word-final [ə] is preserved when an inflectional suffix is added, so the schwa of Rosa’s is similar to the final vowel of Rosa, whereas the unstressed vowel of roses is the high [ī] reduced vowel quality found elsewhere. So the standard transcription of the reduced vowel contrast is justified, but the widespread use of [ə] to transcribe word-internal reduced vowels is misleading—mid reduced vowels are generally only found in stem-final position.
Advances in the acoustic correlates for nasals from analysis of MRI data
Authors: Pruthi Tarun , Espy-Wilson Carol
Published: September 2013

MRI data for nasals is being used to simulate the nasal murmur spectrum in order to improve our understanding of nasals in speech. The data consists of American English nasals /m/, /n/, and /ng/ from one speaker [Story et al., J. Acoust. Soc. Am. 100, 537–554 (1996)]. A computer simulation model developed in our lab is being used for the purpose [Zhang and Espy-Wilson, J. Acoust. Soc. Am. (2004)]. A sufficiently good match has been obtained between the simulated and real spectra, particularly during the low frequencies (below 2000 Hz). Currently, only the maxillary and sphenoidal sinuses have been included in the model. The match between the two spectra is expected to improve further when frontal and ethomoidal sinuses are included in the model. It is our belief that this study will give us a better understanding of the acoustic manifestations of nasal manner and place in the nasal murmur spectrum and help us achieve our goal of finding speaker-independent acoustic parameters (APs) for them. It would also be interesting to see if this study can help us in finding speaker-dependent APs from the nasal murmur spectrum for our speaker recognition system. [Work supported by NSF Grant No. BCS0236707.]
VTAR: A Matlab-based computer program for vocal tract acoustic modeling
Authors: Zhou Xinhui , Zhang Zhaoyan , Espy-Wilson Carol
Published: September 2013

A Matlab-based computer program for vocal tract acoustic response calculation (VTAR) has been developed. Based on a frequency-domain vocal tract model [Z. Zhang and C. Espy-Wilson, J. Acoust. Soc. Am. (2004)], VTAR is able to model various complex sounds such as nasals, rhotics, and liquids. With input in the form of vocal tract cross-sectional area functions, VTAR calculates the vocal tract acoustic response function and the formant frequencies and bandwidths. The user-friendly interface allows directed data input for defined categories: vowels, nasals, nasalized sounds, consonant, laterals, and rhotics. The program also provides an interface for input and modification of arbitrary vocal tract geometry configurations, which is ideal for research applications. [Work supported by NIH Grant 1 R01 DC05250-01.]
Effects of native language experience on perceptual learning of Cantonese lexical tones
Authors: Francis Alexander L. , Ciocca Valter , Ma Lian
Published: September 2013

In a tonal language syllabic pitch patterns contribute to lexical meaning. Perceptual assimilation models of cross-language perception predict speakers of another tonal language should assimilate Cantonese lexical tones to native tonal categories, affecting identification, discrimination and acquisition. For nontonal language speakers, two possibilities exist. If pitch information is ignored, vowels with different tones should assimilate to the same native category, lowering performance. If tonal information is attended but unused in native categorization, Cantonese tones could be nonassimilable and therefore easily discriminated, and possibly easily identified or learned. Here, native speakers of Mandarin Chinese and American English were trained to identify Cantonese words differing in lexical tone. Discrimination and identification were tested before and after training. Both groups initially performed well on upper register tones (high level, high rising, mid level) and poorly on lower (low falling, low level, low rising). Mandarin listeners improved most at identifying low falling tones; English listeners improved most on low level and low rising tones. Training primarily appeared to improve listeners’ ability to make categorical decisions based on direction of pitch change, a feature reportedly under-attended by English speakers, but preferred by Mandarin speakers. [Work supported by research funding from The University of Hong Kong.]
Array processing methods for identifying buried objects
Authors: Bourennane Salah
Published: September 2013

Underwater object identification has been of great interest for a few years to acousticians (detection of boulders) or marines (detection of buried mines). Image and signal processing succeed in identifying objects lying on the sea bottom, however identification of an object buried in sediment remains complex. The purpose of this paper is to develop a complete identification of objects embedded in the sediment using array processing methods. We use a parametric source whose properties are based on the water nonlinear propagation characteristics, the signals are received on a uniform linear antenna. The higher order statistics of the recorded data and the high resolution methods are used to localize the objects and to estimate their ranges. This paper presents also a procedure which estimates discriminant parameters from the signals in order to classify the different objects. The developed algorithms are applied on the experimental underwater acoustic data. The obtained results show the good performance of our algorithms.
Survey of active sonar simulations
Authors: McCammon Diana F.
Published: September 2013

In lieu of well-characterized measured data sets, time series simulations are often employed for testing active sonar systems. This paper reviews the simulation techniques and models that are being employed today and discusses some of the issues of fidelity that may arise with regard to range dependence, bistatic geometries, reverberation statistics and bottom interactions.
Evidence for nonlinear frequency dependence of attenuation in an East China Sea environment
Authors: Knobles David P. , Koch Robert A. , Miller James H. , Potty Gopu R.
Published: September 2013

Acoustic data analyzed from two locations in the central East China Sea indicate a nonlinear frequency dependence of the sediment attenuation. The acoustic measurements are in the form of transmission loss (TL) versus range for frequencies in the 50–800-Hz band and time series generated by explosive sources recorded on a vertical line array (VLA). The seabed can be characterized by a sediment that has a significant sand content. It is discovered that a frequency dependence of fn, with n at least as large as 1.8, is needed to explain both an optimal propagation effect of the TL at the lower frequencies and the temporal spread of the time series measured on the VLA. A linear frequency dependence generates too much loss at the lower frequencies than the reported measurements and impulse responses that have too small of a time spread. Complicating features of the inference of the frequency dependence of the attenuation from forward propagation measurements include the deduction of the source spectrum for individual shots, the source depth, and geoacoustic layering structures that are capable of explaining both measured TL and the time series.
A composer’s eye for room acoustics
Authors: Lucier Alvin
Published: September 2013

The physical acoustician has a number of techniques that can be used to document the acoustic signature of an enclosed space. A composer may approach this matter from a different perspective. This paper discusses and sonically illustrates several physical acoustic aural approaches to developing the signature of a room using unamplified speech and music as source signals. Other methods involving multiple echograms and natural impulse sources are also described. Portions of a score composed for five instruments will be played. In this piece, parts were written for four acoustic instruments as well as for the room in which the performance was presented.
Urban spaces adopted by the performing arts
Authors: Case Alexander U.
Published: September 2013

No celebration of acoustics in New York City would be complete without mention of the countless alternative spaces used for the perfor- mance of music, dance, and other art forms. New York’s countless train stations, parks, alleys, and overpasses provide popular venues for artists to make sound. Lincoln Center and Carnegie get all the glory, but it’s the streets and train stations that do all the work. This work surveys some of these alternative performance spaces and their acoustic contribution to the performance.
Infrasound propagation and coupling between air, soil, and water
Authors: Bass Henry , Talmadge Carrick , Hickey Craig , Desharnais Francine
Published: September 2013

Propagation of low-frequency sound is enhanced by very low absorption in air, water, and soil. Some examples of absorption expected in air, water, and soil are presented. Reduction in sound level between source and receiver is typically the result of spreading. In all media of interest, layering can give rise to trapped waves that decay as cylindrical waves as opposed to spherical waves. Examples of the effect of layering on propagation in the atmosphere will be given for day/night conditions. At very low frequency, scattering by rough terrain, moderate size turbulence, and waves have a reduced effect on signal amplitude and phase. Turbulence carried by the wind can result in pressure variations at the receiver that can sound like acoustic signals. An effective receiving system must deal with that wind noise. Identifying the mechanism for communications at low frequency is complicated by the exchange of acoustic energy between air, soil, and water. Some characteristics of this coupling and losses that might be encountered along different paths will be discussed.
Unusual spatiotemporal patterns in fish chorusing
Authors: D’Spain Gerald L. , Berger Lewis P.
Published: September 2013

An unusual fish chorusing behavior has been observed in nighttime underwater acoustic recordings during the Summer off the Southern California coast. Some characteristics of these choruses, i.e., increases in the ocean sound levels by factors of 2 to 5 for 10 to 20 s followed by 15- to 20-s periods of lower levels, repeating every 30 to 40 s all throughout the night, have been described previously. Recently, in reanalyzing data collected during a set of experiments in which Van Holliday participated, we discovered that the choruses along one 25-km stretch of coastline have characteristics analogous to ‘‘The Mexican Wave’’ performed by spectators at sporting events worldwide. Each cycle of the chorus begins in waters off the Mexican coast and the region of chorusing propagates upcoast until the fish just south of the mouth of San Diego harbor reach a chorus peak 16 to 20 s after their Mexican counterparts downcoast. This pattern repeats at 30- to 40-s intervals. The speed of this upcoast migration is 100 times faster than the 12 m/s human waves in stadia, approaching the 1.5 km/s speed of sound in water. [Work supported by ONR.]
Discrimination of common-envelope signals: Comparison of static and dynamic frequency sounds
Authors: Feth Lawrence , Hudson Dean , Hack Daniel , Rajendran Vivek , Krishnamurthy Ashok
Published: September 2013

Listeners can match the rate of frequency change in an FM glide to the transition rate heard in a virtual frequency (VF) glide. A VF glide is perceived in a two-tone complex when the amplitude of one tone increases, while that of the other tone decreases, over the duration of the signal. This phenomenon is robust for signals spanning five or more auditory filter bands (ERBs). Static two-tone complexes that approximate the end points of the VF glide are discriminable for components separated by more than 20 Hz, but less than five ERB. Preliminary work on discrimination of VF glides versus FM glides processed to have the same envelope as the VF signal led to estimates of just discriminable bandwidth less than one ERB (Rajendran et al., 2003). Center frequencies ranged from 500 to 4000 Hz, but duration was fixed at 250 ms. The preliminary study has been extended to include a range of signal durations from 25 to 250 ms, and to determine the maximum resolution bandwidth for each combination of duration and center frequency. Predictions of the perceptual spectral centroid model will be compared to the results from well-practiced listeners.
Loudness recalibration at short ISI: A closer look
Authors: Arieh Yoav , Mailloux Jennifer R. , Marks Lawrence E.
Published: September 2013

The loudness of a moderate level tone is substantially reduced when preceded by a louder tone of the same frequency (loudness recalibration). The reduction in loudness depends on the interstimulus interval (ISI) between the tones. Arieh and Marks (2003) reported that loudness starts to decline only when ISI exceeds about 200 m. One possible explanation is that loudness reduction takes 200 ms to develop. Alternatively, the delay in loudness reduction could reflect the combination of two processes: short-term facilitation and longer-term suppression. To test this hypothesis, subjects compared the loudness of a roving-level 500-Hz tone to a 60-dB 2500-Hz target tone presented, first, 100 ms after an 80-dB 2500-Hz recalibration tone and, subsequently, with the recalibration tone omitted; by omitting the recent recalibration tone, we hoped to observe the long-term effects on loudness of earlier recalibration tones. As expected, the loudness of the target was unaffected when it followed the recalibration tone by 100 ms, but loudness declined significantly when the recalibration tone was subsequently omitted. These results are consistent with the hypothesis that at short ISI, a recalibration tone sets off long-term suppression of loudness that is initially offset by short-term facilitation.
Speech reception thresholds in various interference conditions
Authors: Carr Suzanne P. , Colburn H. Steven
Published: September 2013

Speech intelligibility is integral to human verbal communication; however, our understanding of the effects of competing noise, room reverberation, and frequency range restriction is incomplete. Using virtual stimuli, the dependence of intelligibility threshold levels on the extent of room reverberation, the relative locations of speech target and masking noise, and the available frequency content of the speech and the masking noise is explored. Speech-shaped masking noise and target sentences have three spectral conditions: wideband, high pass above 2-kHz, and low pass below 2-kHz. The 2-kHz cutoff was chosen to approximately bisect the range of frequencies most important in speech, and the high pass noise condition simulates high-frequency hearing loss. Reverberation conditions include a pseudo-anechoic case, a moderately reverberant ‘‘classroom’’ case, and a very reverberant ‘‘bathroom’’ case. Both binaural and monaural intelligibility are measured. Preliminary results show that source separation decreases thresholds, reverberation increases thresholds, and low frequency noise reverberates more in the rooms, contributing to increasing thresholds along with the effects of the upward spread of masking. The energetic effects of reverberation are explored. [Work supported by NIH DC00100.]
The discrimination and the production of English vowels by bilingual Spanish/English speakers
Authors: Levey Sandra
Published: September 2013

The discrimination of English vowels in real and novel words by 40 bilingual Spanish/English participants was examined. Their discrimination was compared with that of 40 native monolingual English participants. Participants were 23–36 years of age (mean 25.3; median 25.0). Stimuli were presented within triads in an ABX paradigm. This categorial discrimination paradigm was selected to avoid labeling, allowing participants to indicate categories to which stimuli belonged. Bilingual participants’ productions of vowels in real words used in the discrimination task were judged by two independent listeners. The goal was to determine the degree of correlation between discrimination and production. Vowels were studied as these segments present second language learners with more difficulty than consonants. Discrimination difficulty was significantly greater for bilingual participants than for native English participants for vowel contrasts and novel words. Significant errors also appeared in the bilingual participants’ production of certain vowels. English vowels absent from Spanish presented the greatest difficulty, while vowels similar to those in Spanish presented the least difficulty. Earlier age of acquisition, absence of communication problems, and greater percentage of time devoted to communication in English contributed to greater accuracy in discrimination and production. [Work supported by PSC-CUNY.]
Exploring the intelligibilty of foreign-accented English vowels when ‘‘English’’ is ill-defined
Authors: Bundgaard-Nielsen Rikke Louise , Bohn Ocke-Schwen
Published: September 2013

Many studies of foreign-accented speech have been conducted in second language settings in which learners are assumed to be exposed to a relatively homogeneous non-native sound system. However, foreign language learners, who learn an additional language in a setting where this language is not the primary medium of communication, are frequently exposed to a range of varieties of the target language which may differ considerably with respect to their sound systems. The present study examined and compared the intelligibility of English monophthongs produced by two speaker groups: Native Danes who had learned English as a foreign language (with exposure to different native and non-native varieties) and native English speakers from Australia, the US, and the UK. Ten native Canadian-English listeners, who were familiar with native and non-native accents of English, identified the 11 monophthongs of English produced by the speaker groups in a /bVt/ context. As expected, the listeners’ error patterns were specific for each speaker group. However, reduced intelligibility was observed for much the same vowels irrespective of speaker group. Our results suggest that one source of problems in learning the sounds of English is the heterogeneity of English vowel systems in addition to transfer from the native language.
The effects of auditory–visual vowel and consonant training on speechreading performance
Authors: Richie Carolyn , Kewley-Port Diane
Published: September 2013

Recent work examined the effects of a novel approach to speechreading training using vowels, for normal-hearing listeners tested in masking noise [C. Richie and D. Kewley-Port, J. Acoust. Soc. Am. 114, 2337 (2003)]. That study showed significant improvements in sentence-level speechreading abilities for trained listeners compared to untrained listeners. The purpose of the present study was to determine the effects of combining vowel training with consonant training on speechreading abilities. Normal-hearing adults were tested in auditory–visual conditions in noise designed to simulate a mild-to-moderate sloping sensorineural hearing loss. One group of listeners received training on consonants in monosyllable context, and another group received training on both consonants and vowels in monosyllable context. A control group was tested but did not receive any training. All listeners performed speechreading pre- and post-tests, on words and sentences. Results are discussed in terms of differences between groups, dependent upon which type of training was administered; vowel training, consonant training, or vowel and consonant training combined. Comparison is made between these and other speechreading training methods. Finally, the potential benefit of these vowel- and consonant-based speechreading training methods for rehabilitation of hearing-impaired listeners is discussed. [Work supported by NIHDCD02229.]
Role of a carrier sentence in native speakers’ identification of Japanese vowel length
Authors: Hirata Yukari , Lambacher Stephen G.
Published: September 2013

This study examined the role of word-external contexts in native speakers’ identification of phonemic vowel length in Japanese disyllabic nonwords. Three groups of native Japanese listeners (n=20, 20, and 19) were assigned to three conditions differing in word-external contexts. In intact condition, three types of target disyllables /mVmV/, /mV:mV/, and /mVmV:/ were spoken in a carrier sentence at slow and fast speaking rates. In the other conditions, the target disyllables of the intact condition were excised from the original carrier sentence (excised), and embedded in the carrier sentence of the other rate (mismatch). The accuracy for identifying the length of the two vowels was significantly higher for the intact (98.1%) than the excised (69.5%) and the mismatch condition (52.4%). This indicates that the presence of the carrier sentence with an appropriate rate was essential for accurate identification of vowels, consistent with Johnson and Strange [J. Acoust. Soc. Am. 72, 1761–1770 (1982)]. Further analysis indicated that the perceptual errors made in the excised and the mismatch conditions were closely associated with the absolute duration overlap between the short vowels spoken at the slow rate and the long vowels spoken at the fast rate.
Individual differences in speech and nonspeech perception of frequency and duration
Authors: Makashay Matthew J.
Published: September 2013

This study investigates whether there are systematic individual differences in the perceptual weighting of frequency and durational speech cues for vowels and fricatives (and their nonspeech analogs) among a dialectally homogeneous group of speakers. Listeners performed AX discrimination for four separate types of stimuli: sine wave vowels, narrow-band fricatives, synthetic vowels, and synthetic fricatives. Duration and F1 frequency were manipulated for the vowels in heed and hid, and duration and frequency of the fricative centroid in the F5 region were manipulated for the fricatives in bath and bass. Dialect production and perception tasks were included to ensure that subjects were not from dissimilar dialects. Multidimensional scaling results indicated that there are subgroups within a dialect that attend to frequency and duration differently, and that not all listeners use these cues consistently across dissimilar phones. If subgroups can have different perceptions of speech despite similar productions, this questions the requirements for classifying dialect continua. Furthermore, the ratios of these subgroups changing over time can explain some language mergers and shifts. Currently at Army Audiol. & Speech Ctr., Walter Reed Army Medical Ctr., Washington, D.C.
Talker-specific auditory imagery during reading
Authors: Nygaard Lynne C. , Duke Jessica , Kawar Kathleen , Queen Jennifer S.
Published: September 2013

The present experiment was designed to determine if auditory imagery during reading includes talker-specific characteristics such as speaking rate. Following Kosslyn and Matt (1977), participants were familiarized with two talkers during a brief prerecorded conversation. One talker spoke at a fast speaking rate and one spoke at a slow speaking rate. During familiarization, participants were taught to identify each talker by name. At test, participants were asked to read two passages and told that either the slow or fast talker wrote each passage. In one condition, participants were asked to read each passage aloud, and in a second condition, they were asked to read each passage silently. Participants pressed a key when they had completed reading the passage, and reading times were collected. Reading times were significantly slower when participants thought they were reading a passage written by the slow talker than when reading a passage written by the fast talker. However, the effects of speaking rate were only present in the reading-aloud condition. Additional experiments were conducted to investigate the role of attention to talker’s voice during familiarization. These results suggest that readers may engage in auditory imagery while reading that preserves perceptual details of an author’s voice.
Duration as a cue in the distinction between glides and vowels
Authors: Coren A. E. , Warren W. J.
Published: September 2013

This experiment examines the role of length in the perception of glides and vowels. Tokens of the word ‘‘rodeo,’’ spoken at two speech rates, were derived from an original by taking one cycle out of the waveform of the high vowel. Twenty listeners were presented with these derived tokens. It was found that when the length of the first vowel was approximately half that of the second, then 50 percent of the listeners judged the segment a vowel and 50 percent judged the segment a glide. This study agrees with earlier work done in this same manner. It is concluded that in running speech, the relative length of the first vowel is crucial in the vowel versus glide perceptual distinction.
Perceptual relevance of source spectral slope measures
Authors: Kreiman Jody , Gerratt Bruce R.
Published: September 2013

Researchers broadly agree that the spectral slope of the voice source is an important concomitant of voice quality. Many measures of source spectral slope have been proposed, including the relative amplitudes of the lowest few harmonics, the ratio of energy in low- versus high-frequency bands, and the average deviation from an ideal slope. It is unclear which (if any) of these measures best reflects the differences in vocal quality that result from the underlying acoustic variability. To examine this issue, a large corpus of voice samples was inverse filtered, and spectra were calculated for resulting source pulses. Different measures of spectral slope were calculated for each voice, and correlations among measures were examined. Finally, several series of synthetic stimuli were created in which only the source spectral slope varied in steps. Listeners judged the similarity of stimuli within each series. Similarity responses were evaluated with multidimensional scaling, and the resulting perceptual spaces were interpreted in terms of the different measures of source spectral slope. Measures that are highly correlated with the perceptual spaces reflect perceptually important aspects of the source signal. [Research supported by NIDCD.]
Intrinsic fundamental frequency effects in hearing impaired speakers
Authors: Gick Bryan , Bernhardt Barbara , Bacsfalvi Penelope
Published: September 2013

The source of the well-known intrinsic fundamental frequency (IF0) effect of vowel height has been controversial for decades. Previous work has found the average IF0 effect cross-linguistically to be 15.3 Hz [Whalen and Levitt, J. Phonetics (1995)]. The present study investigates IF0 for four hearing-impaired speakers. Based on previous observations that profoundly hearing impaired speakers vary voice pitch less than normal hearing speakers [Osberger and McGarr, Speech Lang. (1982)], our participants were expected to show a reduced IF0 effect. However, results show an average IF0 effect of 22 Hz, with a markedly wide range across speakers, from −4 to 48 Hz, with three of the four participants showing an above average-sized effect. Further, results of measures taken following speech articulation intervention using visual feedback [Bernhardt et al., Clin. Linguist Phonet. (2003)] show a decrease in IF0 for the speakers with an over-sized effect, and an increase in the speaker with an under-sized effect, despite that neither IF0 nor pitch in general were included in treatment. Results of this study support a lingual-articulatory origin for IF0, as well as suggesting that normal-hearing speakers may use auditory feedback to mediate what would otherwise be a larger effect. [Research supported by NSERC.]