bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of formant transition and burst cue integration in stop consonant perception
Authors: Govindarajan Krishna K.
Published: July 2002

While formant transitions and burst cues have been implicated in the place perception of stop consonants, the exact nature of the integration of these cues remains unknown. This study investigates the interaction of these cues by having listeners identify synthetic consonant-vowel (CV) stimuli in which the second formant (F2) transition and the burst center frequency are simultaneously varied in both a front and back vowel context. The resulting identification surface will be presented for the individual subjects, and listeners’ categorizations will be compared to categorization using discrimant analysis and a neural model. Preliminary evidence suggests that the burst center frequency is less critical to identification than which formant it is affiliated with, e.g., F2 or F3. Moreover, in certain contexts, the formant affiliation of the burst overrides the F2 transition information. This result seems to suggests that listeners are interpreting the burst as a formant that starts prior to the other formants, i.e., a ‘‘leading’’ formant. To study this further, the results from another experiment employing synthetic CV stimuli, where one formant leads the other formants, will be presented. [Work supported by NIH Grant DC00194.]
Factors affecting vowel identification in hearing-impaired listeners
Authors: Neel Amy T.
Published: July 2002

Vowel identification generally poses little difficulty for listeners with mild to moderate hearing impairment despite evidence for poorer frequency resolution compared to normal-hearing listeners. Normal-hearing listeners use formant movement and duration cues as well as spectral target cues to identify vowels. This study examines use of formant movement and duration cues by hearing-impaired listeners. Sets of very natural-sounding vowel stimuli with and without formant movement cues (dynamic and static) and with and without duration cues (appropriate and fixed) were made with a new speech resynthesis technique [H. Kawahara, Proc. ICASSP, 1–4 (1997)] using vowels produced by male and female talkers in /dVd/ context. Two groups of young normal-hearing listeners, one with simulated hearing loss typical of 70 year-old males and one control group, displayed no difference in overall vowel identification scores. Both groups obtained significant benefit from tokens containing formant movement cues. Duration was not as effective a cue for vowel identification as formant movement. Results for elderly hearing-impaired and elderly normal-hearing listeners will be presented, and the impact of talker variability upon vowel identification will be discussed. [Work supported by NIH-NIDCD 02229.]
Sound source determination and segregation
Authors: Yost William A.
Published: July 2002

In any medium the auditory system allows one to determine objects in our environment based on the sounds they produce. In a multisource acoustic environment the sounds produced by the sources arrive at the ears as a single sound field. The neural and perceptual processes of the auditory system parse this complex sound field into perceptions of the individual sound sources. There are several key properties of sound that allow the auditory system to determine the aspects of the complex sound field that are associated with each contributing sound source. In order for individual sound sources to be perceived in any medium, these properties must be well preserved in the sound reproduction. This talk will describe the parameters responsible for sound source determination and segregation and one’s ability to perceive individual sound sources in a complex, multisource environment. [Work supported by NICDC, DC000290.]
On the relationship between the subjective preference of sound fields and the α-brain wave in both hemispheres
Authors: Ando Yoichi , Chen Chingyao , Nishio Kazuki
Published: July 2002

For the purpose of finding possible brain activity corresponding to the subjective preference of sound fields, an attempt was made to analyze the effective duration (τe) of the running autocorrelation function (ACF) in the α-wave range (8–13 Hz) in both hemispheres. As the sound source, a music motif (Arnold: Sinfornietta of Opus 48, a 5 s piece of the 3rd movement) was selected. When the temporal factor of the sound fields (the delay time of reflection Δt1) is changed, the values of τe in the α wave in the left hemisphere correspond well with the subjective preference, but not in the right hemisphere. A long value of τe in the α wave indicates the preferred condition. When the reverberation time Tsub is changed, the values of τe in the α wave were much longer at the preferred reverberation time [Tsub]p=1.2 s than those at Tsub=0.2 or 6.4 s in the left hemisphere. On the other hand, when the spatial factor of the sound fields (IACC) is changed, the right-hemisphere dominance is achieved by the analyses of the value of τe in the α wave (p<0.001).
A window into the acoustics of whales and dolphins
Authors: Johnson C. Scott
Published: July 2002

The evolutionary history of dolphins and whales is revealed through extensive adaptation of their sensory systems. Their auditory capabilities were hinted at through their acoustic repertoire after development of the hydrophone. The echolocation capabilities of dolphins, first induced by McBride in 1956, were demonstrated behaviorally in 1958, but nothing was known about their biosonar signals until technology caught up. The revelation that dolphins interrogated their environment using ultrasonic sonar pulses was complemented by demonstration of ultrasonic hearing acuity and sensitivity extending over 6 oct above that of humans. Our understanding of dolphin auditory-filter shapes and receiver-operating characteristics advanced apace with development of instrumentation for underwater acoustics. These findings formed a basis for contemporary research on cetacean psychophysics, anatomy, and acoustical ecology, which continues to reveal the intricacies and elegance of the auditory systems and capabilities of dolphins and whales.
The slippery slope of a Johnsonian ear: Natural variability versus natural loss
Authors: Ketten Darlene R. , Moore Patrick W. B. , Dankiewicz Lois A. , Brill Randall L. , Van Bonn William
Published: July 2002

The normal audiogram of the bottlenosed dolphin, first established by Johnson [C. S. Johnson, in Marine Bio-Acoustics, edited by W. N. Tavolga (1967), pp. 247–260], has been pivotal to nearly three decades of underwater echolocation research, most of which focused on the mechanisms and analytical limits of dolphin sonar. One important aspect of dolphin hearing that has escaped investigation is what are normal audiometric ranges, or, more important, how to determine whether differences seen in audiometric responses of a new animal represent normal variants or a pathologically impaired ear. In this study, radiologic data and audiograms from animals tested by Brill et al. (this session) were compared with results from postmortem histologic analyses of ears from dolphins with known hearing losses. Structural alterations in the ear x rays of the older, male dolphins were consistent with obstructive disease processes and demineralization of temporal bones from dolphins with conductive and progressive sensorineural loss. These findings imply that specific features of the older male’s audiogram, such as the relatively flat, elevated, midfrequency thresholds and the rapid decrement of high-frequency responses, are diagnostic correlates for chronic infection and age-related retrograde neural loss. [Work supported by ONR N000149310940.]
An inversion method for determination of ambient noise due to surf
Authors: Fabre J. Paquin , Wilson James H. , Earle Marshall D. , McDermid Jack G.
Published: July 2002

Ambient noise due to surf has recently been empirically characterized as a source level density (SLD) per meter of beach as a function of wave height and frequency [Wilson et al., IEEE J. Ocean Eng. 22, 425–433 (1997) and J. P. Fabre and J. H. Wilson, IEEE J. Ocean Eng. 22, 434–444 (1997)]. Surf noise depends upon both the source level characteristics of different surf types and the unique propagation conditions from the surf zone seaward. This dependence must be examined in order to develop models capable of providing accurate ambient noise levels in shallow water. An inverse method for determining ambient noise due to surf as a function of beach slope, sediment type, wave type, as well as frequency and wave height is presented. Discussions of incorporating the Navy Surf model into this surf noise prediction method are also provided. A long-term ambient noise data set will be used to validate the method for various environmental scenarios at one location. Using data from other locations, results can be extrapolated to give preliminary estimates of bathymetric and geologic dependencies. The surf SLD as a function of surf type, etc., can be used for any shoreline. This makes it possible to use this model as an inverse noise model to estimate surf conditions on a beach remotely from noise measurements taken offshore.
The influence of rainfall at the ocean surface
Authors: Nystuen Jeffrey A.
Published: July 2002

The underwater ambient sound field can be inverted to detect, classify, and quantify rainfall at the ocean surface. This application of the ambient sound field is explained and used to produce rainfall statistics and event- specific rainfall records over a three-month period from a deep-ocean mooring. The influence of rain at the ocean surface is explored using measurements of near-surface salinity, the surface wave and wind fields, and subsurface acoustic backscatter. Enhanced injection of bubbles into the mixed layer by rain in the presence of high wind is indicated by changes to the shape of the underwater sound spectrum. [Work supported by ONR and NSF.]
Vertical coherence of ambient noise in shallow water: Application to broadband inversions
Authors: Buckingham Michael J. , Deane Grant B.
Published: July 2002

Broadband (200-Hz to 20-kHz) measurements of the vertical coherence of ambient noise have been made in two well-surveyed, shallow-water channels with fluidlike, sedimentary seabeds. The noise at one of the sites, the StrataForm natural laboratory off Eureka, northern California, was occasionally found to be almost exclusively wind generated. Under such conditions, the theoretical coherence, computed using the known properties of the sediment at Eureka, closely matches the data. Subtle effects associated with the depth of the sources (bubbles from breaking waves) are evident above 6 kHz in both the theory and the data. At the second site, in Jellicoe Channel, New Zealand, wind noise was also a major factor but shipping sometimes contributed significantly to the field. Again, theory and data matched well when the known geoacoustic properties of the bottom were used as inputs to the model. Based on these results, it appears that the vertical coherence of ambient noise in shallow water is predictable over a bandwidth as high as 20 kHz, and accordingly has potential as the basis of an inversion technique for obtaining the geoacoustic properties of the sea floor.
On the use of injection molded 1–3 piezocomposite for parametric mode sonar projectors
Authors: Benjamin Kim C. , Moffett Mark B. , Jenne Kirk E. , Konrad William L.
Published: July 2002

Recent experimental studies have indicated that injection molded 1–3 piezocomposite is suited for parametric mode sound generation. Using a new Navy calibration standard (F82), which relies on the 1–3 composite for the active layer, the authors were able to drive the projector at sufficient power levels and measure difference frequency sound fields comparable to conventional diced PZT-based transducer designs. Although the particular 1–3 composite used in the experiment had a low primary mode efficiency, (10 μPa) were realized at a difference frequency of 50 kHz for very modest electric fields (1.5 V/mil). The subject presentation will describe the experimental results as well as include a discussion of modeling issues, and related predicted results. Suggestions will be made for improving the injection molded composite efficiency. [Work supported by NRaD Code D744.]
Dynamic mechanism of micromachined electrostatic airborne ultrasonic transducers
Authors: Ge Li-Feng
Published: July 2002

Micromachining technology allows electrostatic (or capacitive) airborne ultrasonic transducers to be made with highly reproducible characteristics, thus providing the possibility to model their behaviors reliably. The behavior of a transducer depends on its geometric structure and the materials to be used. Its mechanical stiffness results from the compressibility of air in cavities, the bending stiffness of the diaphragm, and the plane tension applied to the diaphragm, if any. It is clarified that there are two main types of dynamic mechanisms according to different structures. In one type in which the air in cavities is enclosed, the diaphragm can be treated as a thin plate supported by an air spring or a plate founded on an air cushion, thus adopting the plate-on-air–spring model or short-tube model, such as those transducers with V-grooved, U-grooved, or pit-array-texture backplates [L.-F. Ge, Chin. Sci. Bull. Acad. Sin. 10 (1997)]. In a second type, air is not enclosed, so that the effect of air spring can be omitted, thereby taking the membrane-under-tension model, such as conventional condenser microphones and ultrasonic transducers with acoustic holes. Resonant frequencies of a transducer can be determined by the vanishing of the reactance of its inversive impedance [L.-F. Ge, J. Acoust. Soc. Am. 96, 3318 (1994)]. [Work supported by the 211 Engineering Foundation of Anhui University.]
Noise in academic environments
Authors: Beristain Sergio
Published: July 2002

In the Acoustics Laboratory of the Faculty of Electrical and Mechanical Engineering of the National Polytechnic Institute (Mexico), a research project on the ‘‘Evaluation of Noise in Academic Environments’’ is under development. During the project, noise measurements have been carried out inside and outside of several educational installations of different grades. This paper summarizes some noise levels and describes critical conditions found in and around schools. Inside schools, the most critical cases were found among the lower educational levels, where kids became quite noisy, depending on the teacher’s authority, and sometimes on the economical condition of students. In other cases, it was the community surrounding some given schools that was the source of the annoying noise. At the bachelor of science and higher levels, it can be said, in general, that noise from the school complexes to the community is irrelevant. Nevertheless, there were periods of time and conditions with high noise levels which affected academic activities. Due to the lack of national standards and recommendations for the evaluation of noise from or to schools, measuring procedures were taken from ‘‘Labor Noise Conditions’’ and ‘‘Noise Sources’’ national standards, and reference was made to international recommendations for classrooms, auditoriums, etc.
Effects of intense noise exposure on the auditory brain-stem response and inner ear histology of fetal sheep
Authors: Pierson Linda L. , Gerhardt Kenneth J. , Abrams Robert M. , Huang Xinyan
Published: July 2002

Past evidence from investigations in which an intense noise was delivered to the fetal hearing mechanism has been contradictory. Some investigations suggest the possibility of a critical period during auditory development when exposure to intense noise may adversely affect auditory function. Other studies have reported no effect of intense noise on the auditory brainstem response of fetal sheep. In one recent experiment, auditory brain-stem response thresholds were recorded in utero from fetal sheep prior to and following an intense broadband noise exposure delivered at a developmental period when the ABR was emerging. The ABR thresholds recorded from the noise-exposed fetuses, when measured over developmental time, were not as sensitive as thresholds obtained from age-matched control fetuses. In a related experiment, sheep were exposed four times to an intense broadband noise and the cochleae were harvested 20 days later for histological analysis. Histological comparisons revealed significant inner and outer hair cell damage in the noise-exposed fetuses. This damage was not observed in control fetuses. These studies provide increased evidence that intense noise delivered to a pregnant ewe can result in alterations of structure and function in the developing auditory system of the sheep fetus.
A modal reduction technique for the finite-element formulation of Biot’s poroelasticity equations in acoustics
Authors: Sgard Franck C. , Atalla Noureddine , Panneton Raymond
Published: July 2002

Recently, finite-element models based on displacement–displacement and pressure–displacement formulations of Biot’s poroelasticity equations have been extensively used to predict the acoustical and structural behavior of multilayer structures. These models, while accurate, lead to large frequency-dependent matrices for large finite-element models and spectral analyses problems necessitating important setup time, computer storage, and solution time. Lately, some authors have established criteria for low-frequency approximations of viscous and thermal effects that allow for a linearization of the poroelastic eigenvalue problem. Complex modes for the damped system or real modes for the undamped system can then be found and used to solve the forced problem. However, this method is not general since it requires assumptions on the porous material physical properties to meet these criteria. It is proposed in this talk to investigate another modal reduction technique. The technique, referred to as selective modal analysis uses a dual basis associated with the skeleton in vacuo and the equivalent fluid in the rigid skeleton limit, respectively. The theory behind the technique will be presented together with numerical examples illustrating its performance.
Sensitivity analysis for vibroacoustic interior problems
Authors: Kao Pi-Jen , Hamdi M. A.
Published: July 2002

A semianalytical sensitivity analysis method is proposed to calculate the eigenvalue and response sensitivity for a coupled vibroacoustic system. This sensitivity information can be used in a design trade-off study or in a formal design optimization procedure. In this study, an acoustic finite-element method is used to compute the eigenvalues, eigenvectors, and responses of the acoustic interior problems. A symmetric form of the coupled equation is used here. By directly differentiating the coupled equation, it can be shown that the sensitivities of the coupled systems depend only on the eigenvalues, eigenvectors, and the derivatives of coefficient matrices of the coupled equation. These coupled sensitivities will be demonstrated for a coupled plate and box problem. Numerical results will be given for the sensitivity of elastoacoustic frequencies due to the change of plate thicknesses and the sensitivity of interior pressures due to the change of acoustic absorbing materials.
Spreading, coherence, fading, and noise in shallow-water channels
Authors: Shockley Richard C. , Rice Joseph A. , McDonald Vincent K.
Published: July 2002

During U.S. Navy undersea acoustic telemetry and ranging (telesonar) engineering tests, probe signals in the 8- to 16-kHz octave will be observed at various ranges and at various locales. Doppler spread and multipath spread will be measured for these waveforms as a function of time. In addition, simultaneous transmission of tonals will allow measurement of the correlation between fades at different frequencies, and hence the coherence bandwidth. Finally, ambient noise will be analyzed for insight into noise statistics and noise nonstationarity. The above information supports signal and receiver design by providing measured, as opposed to theoretical, channel characteristics. These data will also broaden the understanding of geographic and seasonal variabilty of undersea shallow-water channels. This paper describes procedures for extracting these channel statistics from recorded telesonar data. [Work supported by ONR-321.]
Noncoherent communication for adverse channels
Authors: Green Dale , Rice Joseph A.
Published: July 2002

Undersea acoustic telemetry and ranging (telesonar) requires a realistic evaluation of the available physical transmission channel. Benign channels support high-bit-rate coherent transmissions, provided that a suitably powerful channel equalizer is available, and provided that covert signaling is not required. Effective signaling in adverse channels requires accommodation of temporal and spectral dispersion and distortion, mitigation of interference, and asynchronous multiple access by many users. This is attained with frequency-hopped, M-ary FSK signals in which the elemental waveform ‘‘chips’’ are designed to tolerate channel spreading and nonstationarity. The M-ary nature of the signal reduces the needed SNR, while the frequency-hopping patterns inherently provide interference mitigation and multiple access. Specialized signal processing of the received signal effectively yields a channel with uniformly distributed noise in both time and frequency. Residual interference is removed by powerful nonbinary convolutional encoding and related sequential decoding. The sensitivity of signal acquisition and demodulation to errors in estimates of channel parameters is explored. Overly pessimistic estimates of spreading result in reduced channel access and increased interference at the processor output, while overly optimistic estimates result in signal loss and intersymbol interference. [Work supported by ONR-321 and NRaD telesonar Contract No. N66001-96-C-6003.]
Quantitative comparison of two collocated seafloor hydrophone arrays in a shallow coastal water environment
Authors: Stevenson J. Mark , Schmidt Steven L. , D’Spain Gerald L. , Hodgkiss William S.
Published: July 2002

A novel, lightweight shallow-water hydrophone array was deployed and tested alongside a more conventional similar apparatus during the 1996 Adaptive Beach Monitoring Experiment (ABM-96). Controlled J-11 source tows (145-dB tones between 70 and 700 Hz) and local shipping provided a rich assortment of acoustic signals for intercomparison during a 6-h period. The new system, ULITE (ultralightweight sensor system), was deployed alongside the Marine Physical Laboratory’s SRP Array in approximately 13-m water depth. The deployment of ULITE was conducted by hand from a 7-m-long vessel in approximately 1 h. The heaviest component of the system is a 5-kg anchor attached to the end of the ULITE array to prevent movement along the seafloor. Broadcast source tones were observed on single phones in the ULITE array. Received signal excess was, typically, 20–30 dB. The transmissions were simultaneously recorded on the nearby (within 100 m) SRP seafloor array. These data sets represent the first opportunity to conduct a quantitative intercomparison (i.e., single-phone and beamformed spectral ratios) between the ULITE array and a time-proven conventional array. Since the individual hydrophones of both systems are calibrated, a meaningful comparison of absolute levels is possible. [Work supported by ONR 321SS.]
The Office of Naval Research Program to determine the effects of man-made sound on marine mammals
Authors: Gisiner Robert C.
Published: July 2002

Over the past 5 years the Office of Naval Research (ONR) has maintained a coordinated interdisciplinary research program focused on the auditory capabilities of marine mammals, and the potential impacts man-made noise might have by damaging or obscuring that sensory capability. Auditory studies have included behavioral determinations of thresholds to low-frequency sound, effects of depth (pressure) on auditory function, and temporary threshold shift studies. Anatomical data, auditory-evoked potentials and otoacoustic emissions have been explored with the goal of providing larger sampling of populations and enabling sampling of the larger and rarely encountered species, such as baleen whales. The data collected thus far have further strengthened the view that marine mammal hearing represents the pinnacle of development of auditory sensing. With our own use of underwater acoustic sensing in its infancy, it would be wise to closely monitor those activities which might obscure our window into the ocean environment as well as that of its inhabitants who have led us this far.
New vocalization definitively linked to the minke whale
Authors: Gedamke Jason , Costa Daniel P. , Dunstan Andy
Published: July 2002

The description of minke whale (Balaenoptera acutorostrata) vocalizations is sparse with little recent study. In addition, the minke and some of its assumed vocalizations are not definitively linked. To address this problem, recordings were made at a unique site off the Great Barrier Reef where minkes maintain long, close contacts (to 10 h) with vessels. During these encounters a 200-m, four-element hydrophone array (Hi-Tech HTI-SSQ41B, 10 Hz–30 kHz) was deployed and digitally recorded onto a Tascam DA-38 (0–22 kHz). Time of arrival differences between hydrophones were used to obtain hyperbolic fixes on nearby sound sources. With this method, a new vocalization consisting of three short pulses (pulse duration 100 ms, peak energy 200–250 Hz, with significant energy between 1.5 and 2 kHz) followed by a slight upsweep (trail of 1 s) has been definitively linked to the minke. Source levels of at least 155 dB re: 1 μPa were estimated. Similar vocalizations with varying pulse numbers (to at least 7), and low frequency grunts and moans (80–4000 Hz) were recorded. Approximately 19 h were recorded in the close presence of 45 minke whales along with 18 h of ambient recordings. These recordings greatly contribute to the sparse database of known minke vocalizations. [Work supported by ONR and the R/V Undersea Explorer.]
Bionic synthetic aperture sonar
Authors: Altes Richard A. , Moore Patrick W. B.
Published: July 2002

Dolphinlike sonar signals are used to obtain synthetic aperture images of complicated, three-dimensional (3-D) objects from transmitter–receiver positions that are above the plane of effective target rotation. This geometry allows 3-D information to be incorporated into a SAS image. The 3-D information can be represented as a set of spatially registered 2-D (x,y) pixel maps, where each map corresponds to a different focal point in elevation (z). Similar spatially registered environmental maps are used for sensor fusion in the mammalian superior colliculus and in the optic tectum of reptiles and fish. The constant-z maps can be combined to improve the 2-D representation of a 3-D object. For example, the image at a given x,y position can be focused by using pixels from the constant-z map that maximize a local focus criterion at position x,y in the map. Alternatively, a surface recognition criterion yields the z coordinate of the surface of a 3-D object at a given x,y point. The resulting 3-D representation of the object’s surface corresponds to a visionlike representation. These representations can be combined with other spatially registered maps from the visual domain for bionic sensor fusion.
Seismic transmission of elephant vocalizations and movement
Authors: O’Connell Caitlin E. , Arnason Byron T. , Hart Lynette A.
Published: July 2002

Seismic signals were recorded during periods of vocalizations and movement by African and Asian elephants. Initially, vocalizations were detected in both microphone and geophone recordings. To test whether these sounds are propagated separately in the air and the ground, recordings were made with a four-channel data acquisition system, processing signals simultaneously from microphone/geophone pairs at near and remote points ranging from 20–130 m distances from the elephants. These recordings indicate that elephant vocalizations and movement produce Rayleigh waves, a type of ground surface wave. This paper quantifies the propagation of elephant vocalizations in the air and ground and compares the rates of signal attenuation within each of the two media. A normalized cross-correlation coefficient was performed on rumble and movement signals in the ground, resulting in a time lag between near and remote sensors corresponding to Rayleigh wave velocity. Rayleigh waves travel slower than airborne sound waves (approximately 250 m per second versus 340 m per second), but they can travel further and more reliably than those transmitted through the air. The presence of seismic properties in elephant vocalizations and movement suggests a possibility for their use in long distance communication.
Effect of rib bending on Bloch wave structure of a rib-stiffened plate
Authors: Chandiramani Khushi L.
Published: July 2002

It is well known that flexural vibration on a flat plate stiffened by periodically placed line supports shows stop/passband behavior in frequency, associated with Bloch waves. For a one-dimensional situation, with plate vibration incident normally on the ribs, a simple model in which the ribs exert forces normal to the plate by virtue of their mass often suffices to explain stop bands that occur when the rib spacing d accommodates an integer number of the half-wavelengths of plate vibration. This paper presents results for cases where the ribs present normal forces as well as moments to the plate. Particular attention is paid to the case where the rotary impedance offered by the rib is limited by the rib’s own flexibility in bending. At special antiresonance frequencies associated with the rib’s own bending motion, the rib rotary impedance is seen to rise sharply and to give rise to stop bands additional to those generated by the rib normal forces.
Becoming familiar with a talker from natural and sinusoidal sentences
Authors: Sheffert Sonya , Pisoni David , Fellowes Jennifer , Remez Robert
Published: July 2002

This report describes the results of a perceptual training study that was designed to explore how listeners learn to categorize novel voices and how knowledge of a familiar voice generalizes to novel utterances. The speech samples from which the listeners learned to identify individuals were of two kinds: Naturally produced English sentences and sinewave replicas of these sentences. The sinewave items were nonspeech tonal patterns that preserved coarse-grained properties of the talker’s vocal tract transfer function while eliminating traditional cues to voice quality. Listeners were trained over several days to identify ten talkers from sinewave or natural speech sentences. Knowledge about the talker’s voice was then assessed using two generalization tests in which listeners heard a novel set of sentences and identifed the speaker. One generalization test presented sinewave sentences whereas the other presented naturally produced sentences. The results showed that perceptual learning of a talker’s voice can occur even when specific acoustic products of vocal articulation are eliminated from the signal, and that this knowledge generalizes to novel utterances produced by these same talkers. [Work supported by NIH-NIDCD.]
Intelligibility of bandpass-filtered speech
Authors: Stickney Ginger S. , Assmann Peter F.
Published: July 2002

Warren et al. [Percept. Psychophys. 57, 175–182 (1995)] reported high intelligibility for sentences processed by one-third octave bandpass filters. The present study examined the contribution of acoustic and linguistic redundancy to the intelligibility of filtered speech. Separate groups of listeners identified sentences or isolated final words from the SPIN (‘‘speech perception in noise’’) test. One group heard unfiltered speech, while others heard filtered speech with center frequencies of 750, 1100, 1500, 2100, or 3000 Hz. Gammatone filters with bandwidths of 1 ERB were used to match auditory filter widths. Consistent with Warren et al., the 1500-, 2100-, and 3000-Hz bands were more intelligible than the lower bands. Filtered words in high-predictability (HP) sentences were identified more accurately than those in low-predictability (LP) sentences (mean difference 20%). Isolated filtered words were less intelligible than LP sentences (23% difference). Unfiltered HP and LP sentences and final words were equally intelligible, with scores exceeding 94%. Filtered HP sentences were well identified for the 2100- and 3000-Hz bands, with performance similar to unfiltered sentences. These findings support the hypothesis that context is emphasized when the acoustic signal is degraded, and illustrate the interactive nature of multilevel processing.
Rime cognate: A new lexical competitor set for spoken word recognition
Authors: Amano Shigeaki
Published: July 2002

The rime cognate, which is a set of words containing the same phoneme sequence as the rime of a given word, was proposed as a new lexical competitor set for spoken word recognition. Partial correlation analyses showed that the rime cognate has a much larger contribution to the identification of English spoken words than the neighborhood and the cohort which had been commonly used as lexical competitor sets. The analyses also showed that only parts of the neighborhood and the cohort are reliable as lexical competitor sets in spoken word recognition, and that these parts are included in the rime cognate. This result indicates that the rime cognate integrates the two different competitor sets, the neighborhood, and the cohort. Based on these findings, the rime cognate model of spoken word recognition was proposed.
Exploitation of stress information in spoken-word recognition in Dutch
Authors: van Donselaar Wilma , Cutler Anne
Published: July 2002

A fragment-priming experiment addressed the question of how stress information is exploited in the process of recognizing spoken Dutch words. Materials were 20 pairs of Dutch words such as octopus/oktober, with two initial syllables which were segmentally identical but different in stress; both begin okto- (N.B.: in neither case is their vowel reduction, in Dutch), but octopus is stressed on the first syllable, oktober on the second. Exploiting the known effect that visual lexical decisions are made more rapidly if subjects have just heard the word, or part of it, we compared the lexical decision response times of 56 native speakers of Dutch to the target words (e.g., OKTOBER), presented visually immediately following a spoken presentation of a neutral sentence ending with a partial word. This partial word had (a) a correctly stressed beginning (e.g., okTO-), (b) an incorrectly stressed beginning (e.g., OKto-), or (c) a control beginning (e.g., eufo-). Responses were significantly faster (than the control condition) only after correctly stressed primes; that is, OKto- primed OCtopus but not okTOber, okTO- primed okTOber but not OCtopus. Thus Dutch listeners can exploit stress information effectively at a relatively early stage in the spoken presentation of a word.
The effect of masked syllable primes on word and picture naming
Authors: Schiller Niels O.
Published: July 2002

The role of the syllable in Dutch speech production is investigated. Four experiments tested the effect of masked syllable primes on the naming latencies of words and pictures. Target words were bisyllabic Dutch nouns that either had clear syllable boundaries and began with a CV syllable (e.g., fa.kir ‘‘id.’’) or a CVC syllable (e.g., fak.tor ‘‘factor’’), or their syllable boundary was ambiguous, in which case they began with a CV[C] syllable (e.g., fa[kk]el ‘‘torch’’). In the syllable match condition, targets were preceded by syllable primes that were identical to the first syllable. In the syllable mismatch condition, the syllable prime was one segment shorter or longer than the target word’s first syllable. A neutral condition was designed to determine the direction of the priming effects (facilitation or inhibition). All related primes facilitated the naming of the targets significantly, but the priming effect was independent of the syllabic structure of prime and target. It is concluded that the syllable does not play a functional role in the process of phonological encoding in Dutch. Since the size of the facilitation effect increased with increasing overlap between prime and target, the priming effect is accounted for by a segmental overlap hypothesis.
A cross-linguistic study of diphthongs in spoken word processing in Japanese and English
Authors: Yoneyama Kiyoko
Published: July 2002

Utilizing a phoneme-monitoring task, the current study investigates the sensitivity to moraic structure in English and Japanese diphthongs by three groups of language users: monolingual Japanese listeners, monolingual English listeners, and semibilingual Japanese speakers of English. Experiment 1 focused on monolingual Japanese listeners and found that they did not show a moraic effect in English materials, although they did not show that in Japanese materials. Experiment 2 focused on monolingual English listeners and found that they were not sensitive to moraic structure in either English or Japanese, and seemed to listen to both English and Japanese in the same listening strategy. Experiment 3 focused semibilingual Japanese speakers of English and found that they showed a moraic effect in Japanese materials while they did not in English materials. Collectively, findings in experiments 1 and 3 suggest that Japanese natives are generally sensitive to moraic structure. Also, those in experiment 1 and 2 suggest that sensitivity to moraic structure is language specific. Finally, those in experiment 3 suggest that extensive second-language experience allows one to readjust this tuning for each language spoken, such that a listener’s speech segmentation strategy can differ by language.
Accuracy in producing and perceiving vowels in a second language (L2)
Authors: Flege James Emil , MacKay Ian R. A. , Meador Diane
Published: July 2002

The aim of this study was to assess the effect on L2 performance of native Italian subjects’ age of arrival (AOA) in Canada and their percentage use (% USE) of Italian. The 72 native Italian subjects examined had lived in Canada for 36 years, on average. They repeated auditorily modeled English words containing 1 of 11 vowels, then inserted each vowel into a nonword (/b\_m_do/) context. Analyses of listeners’ goodness ratings revealed that subjects with AOAs greater than 10 years produced vowels less accurately than did native English controls. These same subjects produced four English vowels that are not found in Italian (/■ æ ■ ■/) even less accurately in nonwords than in words. This suggested that the ability to establish categories for ‘‘new’’ L2 vowels is age-limited. AOA and % USE were also found to influence the native Italian subjects’ performance on an oddity-format categorial discrimination test which examined contrasts between English vowels (e.g., /■/–/i/) or English versus Italian vowels (e.g., /æ/–/a/). Production and perception accuracy were found to correlate significantly. Taken together, the results support the view that L2 vowel production accuracy is limited by the ability to establish new categories perceptually which, in turn, is age-limited. [Work supported by NIH.]
Speech perception in an individual with verbal auditory agnosia
Authors: Wang Q. Emily , Peach Richard K. , Xu Yi , Manry Charles
Published: July 2002

Verbal auditory agnosia or pure word deafness is a clinical disorder when an individual is able to comprehend written language but unable to comprehend spoken language in the absence of hearing difficulties. It is due to brain damage involving the primary auditory cortex or connections between the thalamus and this area. Although it is a well-known fact that an individual suffering from unilateral auditory agnosia is unable to comprehend speech, it is not clear whether his/her speech acoustic processing as a whole or different aspects of this processing are affected. In an attempt to examine this issue, speech perception ability was tested in an individual who presented with typical clinical behaviors of unilateral verbal agnosia as a result of brain damage involving cortical and subcortical white matter of the left temporal lobe. A series of speech discrimination and identification tests were conducted at two time points: 1 week post onset and 1 month post onset. The testing results indicated that aspects of speech acoustic processing may be differentially affected in unilateral verbal agnosia. [Work supported by Rush University and Northwestern University.]
Aurally aided visual search in depth
Authors: Lim Raymond , Perrott David R. , Gallegos Jose A.
Published: July 2002

Minimum latencies required to locate and identify a visual target (visual search) were obtained in which the visual target could appear in a number of places on a depth plane (0-deg azimuth). A visual target was among the visual distracters located on a finite array segregated at three distances with placement of the target varied within the session from 24 to 232 in. from the subject. The stimulus was a broadband noise (70 dB A). Factoring in the distance of each speaker in relation to the subject, the inverse square law was considered in this paradigm. Four subjects were tested in three conditions: aurally aided search (spatially correlated), aurally unaided search (spatially uncorrelated, where no spatial information was provided), and unaided search (no auditory stimulus was used). The introduction of aurally aided search cues enhanced the ability to localize a target [f(38,84)=2.11, p<0.005], thus lessening the workload on the visual system when distracters were in the visual field. Theoretical aspects and applications will be discussed further.
Improving the acuity and robustness of localization of multiple sources using ‘‘stencil’’ filters
Authors: Liu Chen , Feng Albert S. , O’Brien William D. , Wheeler Bruce C. , Bilger Robert C. , Lansing Charissa R.
Published: July 2002

A biologically inspired localization and speech-enhancement technique, using two microphones, was recently developed for extracting and characterizing a sound in the presence of multiple interfering sources [Liu et al., The Second Biennial Hearing Aid R&D Conference (1997)]. In the previous study, a ‘‘stencil’’ filter was created in the frequency versus intermicrophone phase delay space which significantly enhanced the acuity of sound localization. The stencil followed the multiple curves which represent phase coherence at multiple time differences. However, source artifacts resulted from the curved lines that pose a problem for identifying real versus artifactual sources and for obtaining accurate estimates of sound azimuths. These problems are more severe when the number of sources is large and when some of the sources are less intense than the others. The current study further investigated the role of the curved lines in localization from a weighted stencil filter using different weighting methods. Furthermore, an improvement was made in the localization procedure. By adjusting the weights of the stencil filter, the source artifacts were minimized and the acuity and robustness of localization were increased. The improved algorithm was particularly effective in localizing weak sound sources and in situations having a large number of sources.
Audible apparent movement in depth
Authors: Gallegos Jose A. , Perrott David R. , Lim Raymond , Petrosyan Agavni
Published: July 2002

Auditory apparent movement was studied for source distance in depth varying in both relative and absolute distance. The stimuli consisted of 50-ms broadband noise pulses, each presented at an A-weighted sound-pressure level of 70 dB and at a fixed 0-deg azimuth. Aural targets (ATs) were separated into three distances ranging from 24 to 170 in. The time from onset (interstimulus onset interval or ISOI) of the stimuli varied from 6 to 150 ms. Results indicate that aural apparent movement is readily source displayed in depth (i.e., delta movement). As in studies with apparent movement in lateral dimensions, the relative timing of stimuli is crucial for the appearance of apparent movement [f(8,32)=8.16, p<0.001]. The relative distance between speakers was also found to be a significant factor for the appearance of apparent movement [f(16,64)=3.66, p<0.001]. These findings will be discussed further as they relate to previous research conducted on motion in the auditory system.
Using photoacoustic signals to localize small gas leaks
Authors: Yönak Serdar H. , Dowling David R.
Published: July 2002

In the manufacture of devices that are to be filled with pressurized gases or liquids, efficient localization of leaks is a critical quality control process. Current assembly-line leak localization techniques such as bubble visualization, sniffing devices, or helium-mass spectrometers are either subjective or time consuming. Photoacoustics has already been used to detect small leaks but has not been extended to the localization of these leaks. This work presents a quick and objective leak localization method. Sulfur hexafluoride is used as the tracer gas. Photoacoustic sound is generated by rapidly scanning a carbon dioxide laser tuned to 10.6 μm over a suspected leak area. The sound is measured by multiple microphones. Using the microphone output and signal processing techniques, the location of the leak is determined. Leak location uncertainty due to microphone placement, laser scanning, and leak size is discussed. A signal-to-noise-ratio-dependent leak detection limit is established. Experimental results are presented. [Work supported by Ford Motor Company.]
Sound energy distribution at an intersection of underground tunnels: Full scale experiments
Authors: Imaizumi Hiroyuki , Kinoshita Michiaki , Kunimatsu Sunao , Isei Takehiro
Published: July 2002

Experiments on sound propagation in small-scale tunnels with a branch have been carried out from the viewpoint of safe and rapid information transmission underground. The influences of intersection angles and acoustical properties of inner walls of the tunnels on sound propagation were examined in previous studies [J. Acoust. Soc. Am. 100, 2567 (1996)]. In the present work, sound propagation in a full-scale underground tunnel with a branch is considered. The experimental tunnels are supported by iron frames and concrete lagging, and the cross sections are arch shaped with an area of 4.2 m2. Experimental results indicate influences of the intersection on propagation attenuation at a frequency of around 200 Hz. Whole tendencies of sound attenuation are also affected by relative arrangements of sound source and receivers, and sound attenuates more at the receivers, which are out of sight from the source than for those in sight. For the purpose of the sound-field estimations, the characteristics of sound propagation are examined by numerical calculations us- ing both an analogy with a resonant silencer with a branch and an image source model at the receivers, which are out of sight. Results of the numerical calculations relatively agree with the experimental results.
Room criteria
Authors: Peppin Richard J.
Published: July 2002

This paper presents the status of standards dealing with this very contentious subject. Room criteria are contentious because, for years, the acoustical community has been trying, with minimal success, to come to some consensus on the types of descriptors, measurement procedures, and rating schemes based on steady state noises in rooms. (What constitutes steady state is not agreed upon.) Evidence of this long standing problem is the new ANSI standard S12.2-1995: Even though written after perhaps 10 years effort, it is still not satisfactory to many, if not most, people. This presentation tries to provide a perspective on this issue, not from an expert’s point of view, but from someone immersed in the controversy for a long time. The issues that need to be addressed, the current and proposed methods, and the problem with data collection, funding, and research will be discussed. Audience input and reaction will be solicited if time permits.