bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of frequency modulation of the ability to judge dynamic changes in interaural level differences
Authors: Whitmer William M. , Dye Raymond H.
Published: July 2002

The cues for apparent auditory motion include dynamic interaural temporal differences, level changes, and frequency modulation (FM) [Rosenblum, Perception 16, 175–186 (1987)]. The manner in which these cues interact was examined in a task in which listeners judged the point at which a stimulus having dynamic changes in interaural level difference (ILD) passed through the intracranial midline. In base-line conditions, stimuli were 2.0–2.5-s, 0.5- or 2-kHz sinusoids presented through headphones. In experimental conditions, a frequency-modulated tone was added. Frequency was modulated by a linear ramp or according to a Doppler-based algorithm. The midpoint of the frequency-sweep occurred either at the instant that the ILD passed through 0 dB, acting as a task cue, or at some other point. FM rate and magnitude, temporal position of frequency-sweep midpoint, and direction of apparent movement were randomized across trials. Results indicated that the presence of FM had a significant effect on the perception of intracranial midline. This effect was obtained across FM parameter values. Results were considered in terms of how dynamic cues for perceived motion perceptually interact. [Work supported by NIH and AFOSR.]
Does precedence prevail through sudden changes in selected partials of a complex natural spectrum?
Authors: Valenzuela Miriam N. , Hafter Ervin R.
Published: July 2002

Localization of a source followed by a delayed version of it from another direction is dominated by the direction of the first wavefront. It has been suggested that this ‘‘precedence’’ effect and its implication of echo suppression is a dynamic process, subject to listeners’ expectations about what a ‘‘plausible’’ echo should be. The present study investigates what makes an echo ‘‘plausible’’ [Rakerd and Hartmann, J. Acoust. Soc. Am. 78, 524–533 (1985); Clifton et al., J. Acoust. Soc. Am. 95, 1525–1533 (1994)]. Synthetic piano tones presented through pairs of speakers in an anechoic room were designed to simulate natural sounds heard in echoic environments. Trials consisted of conditioning stimuli followed by a test stimulus. Each stimulus was made up of a hypothetical source and echo. The spectra of the test echoes could be changed to reflect abrupt changes in the absorption qualities of simulated reflections. As in precedence, conditioning stimuli were localized in the direction of their sources. Attenuation of selected partials in the test-echo did not break down precedence, but when the echo-spectra were modified in less plausible ways by amplification of selected partials, precedence broke down.
Reducing hearing protector test time with a minimum audible pressure to field transfer function
Authors: Murphy William J. , Franks John R.
Published: July 2002

Effective hearing-loss prevention programs should train workers to properly fit hearing protection devices. In order to minimize the training time for protector fitting, unoccluded minimum audible field threshold (MAF) for narrow-band noise could be estimated from the worker’s annual minimum audible pressure (MAP) audiogram. Murphy et al. previously reported a transfer function for 5- and 1-dB audiometry for 75 and 10 subjects, respectively [W. J. Murphy, J. R. Franks, S. L. Hall, and E. F. Krieg, J. Acoust. Soc. Am. 101, 3126 (1997)]. Significant differences at several frequencies between the 1- and 5-dB groups prompted further study of the transfer function. This paper reports MAF and MAP results for 44 subjects tested with both 1- and 5-dB audiometry and 1-dB sound field. Pure-tone thresholds were significantly different, for 1- and 5-dB step sizes. The binaural reference equivalent threshold sound pressure level (RETSPL) sound-field thresholds were compared with the RETSPL thresholds for monaural listening in a sound-field listed in ANSI S3.6-1996, Table 9. The binaural thresholds were found to be significantly higher (p<0.05) than the standard values at all frequencies except 8000 Hz.
Modeling tremulous voices
Authors: Kreiman Jody , Gabelman Brian , Gerratt Bruce R.
Published: July 2002

Vocal tremors prominently characterize many pathological voices, but acoustic–perceptual aspects of tremor are poorly understood. To investigate this relationship, two tremor models were implemented in a custom voice synthesizer. The first modulated F0 with a sine wave. The second provided ‘‘random’’ modulation based on white-noise low-pass filtered with cutoff frequency equal to the nominal modulation rate (usually 1–10 Hz). Control parameters in both models were the rate and extent of F0 modulation. (Amplitude modulation was not separately modeled.) Thirty randomly selected 1-s samples of /a/ were modeled. Two synthetic versions of each vowel were created: one with tremor parameters derived from plots of F0 versus time, and one with parameters chosen to match the original stimulus auditorily, regardless of measured tremor values. Listeners judged the similarity of each synthetic voice to the original stimulus. Sine wave and random tremor models both provided excellent matches to subsets of the voices. Preliminary results suggest that tremor rates could be satisfactorily derived from F0 plots, but tremor deviations derived from these plots sounded too extreme. These results also demonstrate the advantage of this perceptual analysis-by-synthesis method in integrating acoustic and perceptual approaches to measuring voice quality.
Using time-temperature superposition to estimate the elastic shear modulus and dynamic viscosity of human vocal fold tissues at frequencies of phonation
Authors: Chan Roger , Titze Ingo
Published: July 2002

The principle of time-temperature superposition [J. D. Ferry, Viscoelastic Properties of Polymers (Wiley, New York, 1980), pp. 264–320] has been widely used by rheologists to estimate the viscoelastic properties of polymeric materials at time or frequency scales not readily accessible experimentally. This principle is based on the observation that for many polymeric systems molecular configurational changes that occur in a given time scale at a low temperature correspond to those that occur in a shorter time scale at a higher temperature. Thus the viscoelastic properties of these systems empirically measured at various temperatures at a certain frequency are indicative of measurements at different frequencies at a single reference temperature. Using a rotational rheometer, the elastic shear modulus and dynamic viscosity of human vocal fold mucosal tissues were measured at relatively low temperatures (5–25°C) at 0.01–15 Hz. Data were empirically shifted based on this principle to yield a composite ‘‘master curve’’ which gives a prediction of the shear properties at higher frequencies at 37°C. Results showed that the time-temperature superposition principle may be used to estimate the viscoelastic shear properties of vocal fold tissues at frequencies of vocal fold vibration, on the order of 100 Hz. [Work supported by NIH Grant No. P60 DC00976.]
Variations in temporal patterns of speech production among speakers of English
Authors: Smith Bruce L.
Published: July 2002

Results from most studies concerning temporal properties of English are typically presented as group averages. Although various trends emerge from such analyses, relatively little is known about the extent to which individual speakers actually exhibit these tendencies. While some amount of variation among subjects is to be expected, it is also important to determine how regularly individual speakers manifest such temporal patterns. The present study examined several hundred productions by each of 10 native, adult speakers of English to assess the extent to which they showed various temporal characteristics. While a majority of subjects demonstrated, in varying degrees, most of the temporal patterns considered, some did not. For example, most speakers exhibited phrase-final vowel lengthening, averaging approximately a 20%–25% increase for the group across several different words; however, several speakers either did not show phrase-final vowel lengthening for any stimuli, or they showed it for certain words but not others. In addition, the range of performance among speakers who did manifest phrase-final vowel lengthening varied from as little as 5% increases for some stimuli to more than double for others. Implications of these findings for development, second language acquisition, etc., will be discussed.
Place of articulation for consonants: Comparing nasals and stops, and syllable position
Authors: Stevens Kenneth N. , Manuel Sharon Y. , Matthies Melanie L.
Published: July 2002

This study reports on measurements of transitions of the second formant (F2) for syllable-initial and syllable-final nasal and stop consonants in English, as cues to place of articulation. F2 values and the amount and direction of F2 changes in a 20 ms interval were determined in vowels adjacent to consonant ‘‘implosion’’ and release. The corpus included consonants in sentences and isolated nonsense syllables. The F2 transitions for a given place of articulation are roughly similar for nasals and stops for different syllable positions, as expected, but some interesting differences exist. Since the stop-consonant bursts influence the spectrum sampling point relative to release, there are some shifts in F2 onset frequencies for stops, as compared to nasals. Syllable-initial alveolars show additional manner differences, which can be attributed to differences in tongue configurations for alveolar nasals relative to stops in back-vowel contexts. These latter shifts are tentatively ascribed to differential coarticulatory effects for /n/ versus /d/ and /t/ differences which might be related to the lack of a distinctive syllable-initial velar nasal in English. There are also systematic shifts in F2 transitions as a function of syllable position, for both nasals and stops. [Supported in part by NIH Grants DC00075 and DC02525.]
Attention and laterality preferences in children who clutter
Authors: Blood Gordon W. , Blood Ingrid M. , Tellis Glen W.
Published: July 2002

Children who clutter were compared to children who stutter and children who did not stutter on a synthetically generated dichotic consonant-vowel listening task and a timed response assessment task of attention. The Dichotic Listening Test consisted of 120 pairs of synthetically generated stop consonants. Subjects used a pointing response and tasks involved three listening conditions (free recall, directed left, directed right). The Conners’ Continuous Performance Test was used to obtain an overall attentional index score, number of correct responses, percentage of omissions, percentage of commissions, hit reaction time, and beta and sensitivity scores. Results revealed that during the directed right and directed left listening tasks children who cluttered and control subjects showed right and left ear advantages. Children who stuttered demonstrated mixed laterality on the DLT. It appeared that children who cluttered benefitted directly from a task which directed their attention to a specific ear. Results of the Continuous Performance Test supported this hypothesis. Children who cluttered showed poorer performance on the overall attentional index as well as a number of the subscores than children who stuttered and children who did not stutter. Implications for future research will be discussed.
Which dyslexic children have speech perception difficulties?
Authors: Keating Patricia A. , Joanisse Marc F. , Manis Franklin A. , Seidenberg Mark S.
Published: July 2002

The incidence of speech perception difficulties, and their co-incidence with other impairments, were examined in third-grade poor (bottom-quartile) readers. Several subgroups of dyslexics, plus age and reading-level controls, were compared in their identification of /d/ vs /t/ in a ‘‘dug–tug’’ continuum, and /p/ vs /k/ in a ‘‘spy–sky’’ continuum. Only those dyslexics who also did poorly on two standardized language tests of inflection and vocabulary—9 of 63 dyslexics—differed from controls in performance on these speech sound categorization tasks, with shallower categorizations. In contrast, dyslexics who did poorly on a test of phoneme deletion, but normally on the language tests, performed like controls in speech perception. Thus an association was found between speech perception and morphological/lexical knowledge, but not between speech perception and phonological knowledge—an unexpected result. A follow-up study tested AX discrimination using the ‘‘spy–sky’’ stimuli. The same dyslexic children who had done poorly on the identification tasks differed from controls in discrimination; the other dyslexics again performed like controls. However, the deficit of the poorer perceivers is not auditory—their across-category discrimination was normal, and their within-category discrimination better than normal. Thus their difficulty is specifically with speech sound categorization. [Work supported by NICHD, NIMH, and NSERC.]
Relationships between expressive vocabulary size and spoken word recognition in children
Authors: Munson Benjamin
Published: July 2002

Studies have shown that children require more acoustic information than adults to accurately identify spoken words [Munson et al., J. Acoust. Soc. Am 99, 2591 (1996)]. In this study, 61 children aged 3.0 to 7.11 were tested to assess whether spoken word recognition accuracy was predicted by scores on standardized tests of expressive and receptive vocabulary, articulation ability, preliteracy skills, and phonological awareness. Two word recognition tasks were used: a gated series [Elliot et al., Percept. Psychophys. 42, 150–157 (1987)] in which subjects identified CVC words with missing final consonants, and a noise-center series [Fox et al., J. Speech Hear. Res. 35, 892–902 (1992)], in which subjects identified CVC words with the medical vowel replaced by noise. Each task had four experimental conditions. Subjects’ age predicted a significant proportion of variance in word recognition scores on the five conditions for which the majority of subjects performed above chance. Additionally, scores on a test of expressive vocabulary predicted a significant proportion of variance in two of these five conditions. No other test predicted relationships between expressive vocabulary growth and developmental changes in spoken word recognition. [Work supported by NIH.]
Masked temporary threshold shift (MTTS): A relevant measure for hearing shifts in open waters
Authors: Ridgway Sam H. , Carder Donald A. , Finneran James J. , Schlundt Carolyn E.
Published: July 2002

Cetaceans use sound in foraging, communication, and navigation. There is growing concern that human-made sound is a potentially serious auditory problem for cetaceans. Available data were inadequate to allow confident predictions regarding the levels of sound that should be of concern. An accepted method of determining the level of sound that produces a temporary reduction in the ears ability to respond fully is called temporary threshold shift (TTS). In the open waters of San Diego Bay, masked hearing thresholds were estimated for dolphins, Tursiops truncatus, and white whales, Delphinapterus leucas, before and after exposure to louder 1-s tones at five sonar frequencies. Masking noise was used to create a floor effect, thereby eliminating threshold variability in the ever-changing ambient noise environment in the natural waters where tests were conducted. The criterion for masked TTS (MTTS) was a 6-dB increase in threshold over baseline. Subjects exhibited alterations in their behavior starting at levels around 180 dB, and experienced MTTS at levels between 192-202 dB. Maximum levels of sound exposure without risk of hearing damage can be determined with the MTTS approach. More research employing different sound sources is needed. [Supported by Office of Naval Research.]
Thin, low-frequency sound projectors for use in shallow water
Authors: Tressler James F. , Howarth Thomas R.
Published: July 2002

A thin, low-frequency acoustic projector is being developed at the Naval Research Laboratory for shallow water applications. The active panel consists of cymbal-type flextensional driver elements arranged individually behind an acoustic radiating plate. Variants of two panel designs have been calibrated underwater. The acoustic projector sandwich is nominally 6.35 mm thick and is intended to operate between 1 and 10 kHz. The calibration results that will be presented (TVR, SPL, directivity response) will focus primarily on a panel consisting of 12.7-mm-diam cymbal elements arranged in an 8×8 square configuration. [This research is being supported by Code 321SS of the Office of Naval Research.]
Reduction of measurement variation: Small acoustic chamber screening of hard disk drives
Authors: Ogle Tami , Hornberger Lee
Published: July 2002

Several small acoustic chambers on the manufacturing floor are used at Western Digital to screen out unacceptably loud disk drives. The screening test initially had large variation which made its effectiveness questionable. It was unclear whether this variation was coming from the drives or the chambers. In this study statistical methods were used to determine the source of the variation, and a design of experiments approach was used to determine the factors which significantly contributed to the variation. It was determined that the measurement chambers, not the drives, were the source of the large variation in testing. Additionally, the significant factors affecting the screening test were found to be the microphone calibration and microphone height inside the chamber.
Changes in attenuation in personal hearing protector over time during use
Authors: Valoski Michael P. , Durkt George
Published: July 2002

Ideally, implementing engineering controls reduces workers noise exposures below the permissible exposure level (PEL). However, some occupations continue to have exposures above the PEL. To protect the hearing sensitivity of these workers, personal hearing protectors (PHP) must be worn. Manufacturers test PHPs under ideal conditions in a laboratory. For these tests, highly motivated and trained subjects remain stationary. Furthermore, a researcher helps the subject fit the PHP. Shortly after determining that the PHP was properly fitted, the tests are conducted. Under these conditions the optimum attenuation afforded by the PHP is achieved. Mining conditions differ substantially from those under which the laboratory attenuations are determined. Often, workers wear their PHPs for extended periods without removal. Moreover, a worker’s constant movement may disrupt the seal of a PHP. Once the seal is broken, the PHP provides degraded performance. This project examines any change in earmuff attenuation over a 3-h wearing time in a laboratory. After donning an earmuff unaided, a subject wore the earmuff for 3 h while walking and stopping to lift containers from the floor to a table in a large reverberation chamber. It was found that the PHP’s attenuation did not change substantially during the test.
Attenuation in tertiary gas mixtures with two relaxing components
Authors: Dain Yefim , Lueptow Richard M.
Published: July 2002

Vibrational relaxation accounts for absorption and dispersion of acoustic waves in gases that can be significantly greater than the classical absorption mechanisms related to shear viscosity and heat conduction. This vibrational relaxation results from retarded energy exchange between translation and intramolecular (vibration) degrees of freedom. Theoretical calculation of the vibrational relaxation time of gases based on the theory of Landau and Teller [Phys. Z. Sowjetunion 10, 34 (1936)] and Schwartz et al. [J. Chem. Phys. 20, 1591 (1952)] has been applied at room temperature to the polyatomic mixtures of nitrogen with water vapor and methane as relaxing components. The theory accounts for vibrational–vibrational coupling of all constituents together with vibrational-translational energy transfer. For negligible concentrations of methane and small vibrational–vibrational coupling the analytical expression matches previous theoretical and experimental results for the binary nitrogen–water mixture. For tertiary nitrogen–water–methane mixtures, the humidity and methane dependence of the nitrogen relaxation frequency differs from that of binary mixtures of either component with nitrogen due to coupling between the components. The significance of vibrational–vibrational coupling of binary pairs in the tertiary mixture has been analyzed.
Thermoacoustic properties of nonuniform stacks
Authors: Petculescu Gabriela , Wilen Larry A.
Published: July 2002

Thermoacoustic stacks of uniform cross section can be characterized completely in terms of the single thermoviscous function F(λ) [W. P. Arnott, H. E. Bass, and R. Raspet, J. Acoust. Soc. Am. 90, 3228–3237 (1991)]. For nonuniform stacks, one must treat thermal diffusion and viscosity separately, and it may be possible to ‘‘tune’’ the performance of the stack by taking advantage of the extra geometric freedom. Measurements have been performed to determine the thermoviscous characteristics of pin-like stacks for which the elements are oriented either along, or perpendicular to, the temperature gradient. The measurements characterize terms in the thermoacoustic equations responsible for thermal dissipation and thermoacoustic gain. The results for pins of varying size, shape, and spacing will be discussed. Time permitting, applications of novel designs to compact lumped element oscillators will be demonstrated. [Work supported by the Office of Naval Research.]
Thermoacoustics of moist air with wet stacks
Authors: Slaton William V. , Raspet Richard
Published: July 2002

Recent work in porous media has led to an analytical treatment of sound in wet-walled tubes [Raspet et al., J. Acoust. Soc. Am. 105, 65–73 (1999)]. This work has been extended to examine thermoacoustic refrigerators which utilize moist air at atmospheric pressure as the working fluid as described by Hiller [Thermoacoustic Review Meeting 1999, National Center for Physical Acoustics]. In the described system the moisture in the air stream is cooled below its dew point and appears as either liquid on the stack surface or as a fog. This physical system can be adequately described by ignoring thermal diffusion of the water vapor (Soret effect) and neglecting temperature variations in the tube wall. The effects on sound propagation and efficiency due to the presence of liquid water in the system described above will be discussed. [Work supported by ONR.]
On loudness and pitch of ‘‘complex noise’’ in relation to the factors extracted from the autocorrelation function
Authors: Sato Shin-ichi , Sakai Hiroyuki , Ando Yoichi
Published: July 2002

In a previous study, it was shown that the loudness of bandpass noise within the critical band changes increasing the effective duration of the envelope of the normalized autocorrelation function (ACF) τe changing the filter slope of bandpass noise and the subsequent reverberation time Tsub of sound field [Y. Ando, Architectural Acoustics—Blending Sound Sources, Sound Fields, and Listeners (AIP Press/Springer-Verlag, New York, 1998), Chap. 6]. In this study, the loudness of the complex signals including bandpass noises with different frequency (complex noise) is examined. The complex noises consist of the bandpass noises whose center frequencies are the harmonics of the fundamental frequency. The bandwidth of each component is changed within the critical band by use of a sharp filter of more than 1000 dB/octave. Subjects judge the loudness of complex noise by comparing the tone of its perceived pitch frequency, the ‘‘missing fundamental.’’ The results are discussed with the four factors extracted from the autocorrelation function, which are τe, the energy represented at the origin of the delay Φ(0), and the amplitude and the delay time of the first peak of ACF φ1 and τ1. [Work supported by ACT-JST and Grant-in-aid for Scientific Research, JSPS, Japan.]
Sound quality judgments of everyday sounds
Authors: Kidd Gary R. , Watson Charles S.
Published: July 2002

An experiment was conducted to determine the psychological dimensions that underlie listeners’ judgments of the qualities of everyday sounds and to identify the stimulus properties on which such judgments are based, using Osgoods’ semantic differential technique. A collection of 145 common sounds was presented to 32 listeners who rated the sounds on 20 seven-point rating scales. The sounds were of a variety of common objects and events (e.g., dishwasher, vacuum cleaner, door closing) as well as ambient sounds that sometimes involved several objects and events (e.g., traffic, cafeteria noise, rain). Rating scales included subjective adjective pairs (e.g., happy–sad, relaxed–tense) and objective pairs (e.g., hard–soft, large–small). A principal components analysis of the rating data indicated that average judgments of the listeners were associated with four dimensions, roughly corresponding to large–small, compact–scattered, harsh–mellow, and overall quality (high–low). However, the level of agreement across subjects varied considerably for the different sounds and rating scales. The relations between several static (averaged over the entire waveform) and dynamic (time-varying) stimulus properties and listeners’ judgments will be discussed. [Work supported by NIH/NIMH.]
Observer weighting of monaural level information in a pair of tone pulses
Authors: Stellmack Mark A. , Viemeister Neal F.
Published: July 2002

In a cued single-interval task, listeners were presented a pair of standard pulses (each 10 ms, 1 kHz) of fixed level followed by a pair of similar tone pulses, the comparison, separated by a fixed interpulse interval (IPI of 2–256 ms. Listeners were instructed to attend to either the first or second pulse of the comparison and to indicate whether the target pulse was higher or lower in level than the corresponding pulse of the standard. The levels of the pulses in the comparison were selected randomly and independently in each trial (μ=75 dB SPL, σ=8 dB). The relative weight given to each pulse was obtained by computing the correlation between the level of the first or second pulse in dB and the listener’s responses. Listeners adjusted their weighting strategy most appropriately for the given task at the largest IPI. as IPI decreased, listeners gave increasingly similar weight to the two pulses for both target positions. This suggests that level information was integrated across the pulses. Thus, it appears that in certain situations integration of level information occurs over much larger time intervals than previously supposed. The data are not consistent, however, with simple temporal integration of the pulses. [Work supported by NIH DC 00683.]
Wave propagation experiments using point load excitation in a multi-layered structure
Authors: Zhou Chunnan , Achenbach Jan D. , Popovics John S.
Published: July 2002

Transient wave propagation measurements on a single plate, a two-layer plate and a two-layer-on-a-half-space structure are reported. The experiments are performed using point load excitation and point detection at the surface of the structure. The experimental results are used to verify the accuracy of a new model for wave propagation in layered structures. The basis of the model is first introduced. Experimental measurements using different wave sources, plate materials and wave sensors are compared with each other and with theoretical results. The actual source functions for pencil-lead-break wave sources are obtained. Next, experiments performed on an aluminum plate bonded to a stainless steel plate are reported. Both the cases of stainless steel atop aluminum and aluminum atop stainless steel are considered. The experimental results show good agreement with the theoretical predictions. The effects of the second layer on the transient displacement of the top surface are discussed. Finally, a two-layer-on-a-half-space structure consisting of a stainless steel plate as the top layer, an aluminum plate as the second layer and a thick acrylic resin block as the half-space is studied. The presened experimental transient measurements agree with the predicted results, thus verifying the accuracy of the model.
Effects of talker differences in vowel production on vowel identifiability
Authors: Neel Amy
Published: July 2002

Normal talkers differ in speech intelligibility, and vowel production characteristics contribute to intelligibility. This study investigated the relation between talker’s acoustic vowel characteristics and the identification of their vowels by normal-hearing listners. Static and dynamic characteristics were measured for ten American English vowels producted in /dVd/ context by two female and two male talkers. Listeners identified four types of resynthesized vowels for each talker, ranging from nearly natural tokens with dynamic formants and appropriate duration values to relatively impoverished tokens containing only static formants and no duration cues. Significant differences in identification scores among talkers were found. The talker with the best-identified vowels, a male, had the largest and most dispersed vowel space with little overlap of formant trajectories in the dynamic F1×F2 space. The worst talker, also male, had a smaller vowel space with greater overlap of formant trajectories. For all four talkers, dynamic-formant vowels were better identified than static-formant vowels, and there were greater differences among talkers for dynamic-formant vowels than for static-formant vowels. The results confirm that formant movement contributes to vowel identification and that greater separation in the dynamic F1×F2 space contributes to better vowel identifiability.
The perception of noise vocoded prevocalic stop bursts and formant transitions
Authors: Kiefte Michael
Published: July 2002

Theories of prevocalic stop consonant perception differ with respect to the amount of spectral resolution required by the model, e.g., gross spectral shape theories predict that human speech perception is more robust against decreased frequency selectivity where detailed cues such as vocalic formant transitions break down. Previous results in the perception of noise vocoded speech [M. Kiefte, Int. Conf. Phon. Sci. (1999)] showed that, although listeners’ performance worsened significantly at bandwidths as low as 500 Hz, a spectral shape model using cepstral coefficients was better able to predict subjects’ responses. However, a simulation which showed that release bursts require much less spectral resolution than vocalic formant transitions complicates the interpretation. Therefore, in this experiment, subjects were asked to identify the place of articulation for gated release bursts independently of vocalic portions for both unprocessed and noise channel vocoded speech. Preliminary results show that correct identification of stop place from only the release burst does not change significantly up to a channel bandwidth of 2000 Hz. Results suggest that responses from the previous experiment can be explained by the robustness of the burst in those stimuli. Gross versus detailed cue models are also evaluated with respect to responses to formant only stimuli. [Work supported by SSHRC.]
An fMRI investigation of feature distinctions in consonant identification
Authors: Doeleman Tobey L. , Hirsch Joy
Published: July 2002

Differences in neural activation associated with the voicing and place distinctions of phonemes were investigated using functional magnetic resonance imaging (fMRI). Two types of synthetic stimuli were presented auditorily in a forced-choice identification task: clear CV syllables and CV syllables whose initial consonants were ambiguous with regard to either place or voicing. The stimuli consisted of the consonants [p, b, t, d, k, g] followed by the vowels [a, i, u]. Subjects were asked to match each auditory stimulus with one of two visually presented choices representing either voicing-feature or place-feature alternatives. Results consistently showed more widespread activation for all subjects in Wernicke’s area (Brodmann’s area 22) associated with determining the voicing feature versus the place feature of a phoneme. This finding is consistent with previous behavioral results [T. L. Doeleman, J. Acoust. Soc. Am. 101, 3111(A) (1997)] showing more voicing than place errors in consonant identification and suggests a difference in the relative difficulty of these featural decisions. The fMRI design also allowed for a comparison of activiation associated with identifying clear versus ambiguous phonemes. Results show a trend of greater activation, especially in the right hemisphere, associated with the ambiguous stimuli.
The effects of high-intensity speech on consonant feature transmission in normal-hearing subjects
Authors: Hornsby Benjamin W. Y. , Grantham D. Wesley , Ohde Ralph N. , Ashmead Daniel H. , Trine Timothy D.
Published: July 2002

The effect of high-speech presentation levels on consonant recognition and feature transmission was assessed in normal-hearing subjects. Consonant recognition of C/i/ nonsense syllables was measured at five overall speech levels ranging from 65 to 100 dB SPL. Audibility remained constant by mixing speech stimuli with a speech-shaped noise at a constant 0-dB signal-to-noise ratio. Consistent with the work of others, overall percent correct performance decreased as the presentation level of speech increased [Studebaker et al., J. Acoust. Soc. Am. 105, 2431–2444 (1999)]. Confusion matrices were analyzed in terms of relative percent information transmitted at each speech presentation level, as a function of feature. Six feature sets (voicing, place, nasality, duration, frication and sonorance) were analyzed. Results showed the feature duration (long consonant duration fricatives) to be most affected by increases in level while the voicing feature was relatively unaffected by increases in level. In addition, alveolar consonants were substantially affected by level while palatal consonants were not.
Perception of stress and speaking style for selected elements of the s
u
s
a
s database
Authors: Bolia Robert S. , Slyh Raymond E.
Published: July 2002

The susas database [J. H. L. Hansen and S. E. Bou-Ghazale, EUROSPEECH 97, 1743–1746 (1997)] is a collection of utterances recorded under conditions of simulated or actual stress, the purpose of which is to allow researchers to study the effects of stress and speaking style on the speech waveform. The aim of the present investigation was to assess the perceptual validity of the simulated portion of the database by determining the extent to which listeners classify its utterances according to their assigned labels. Seven listeners performed an eight-alternative, forced-choice, judging whether monosyllabic or disyllabic words spoken by talkers from three different accent classes (Boston, Generic Midwest, New York) were best classified as ‘‘angry,’’ ‘‘clear,’’ ‘‘fast,’’ ‘‘loud,’’ ‘‘neutral,’’ ‘‘question,’’ ‘‘slow,’’ or ‘‘soft.’’ Mean percentages of ‘‘correct’’ judgments were analyzed using a 3 (accent class)×2 (number of syllables)×8 (speaking style) repeated measures analysis of variance. Results indicated that, overall, listeners correctly classify the utterances only 58% of the time, and that percentage of correct classifications varies as a function of all three independent variables.
Interpreting Garner interference
Authors: Weil Shawn , Pitt Mark
Published: July 2002

The Garner (1974) speeded classification procedure has long been used in psychoacoustic, speech perception, and music perception research to assess the relative integrality or separability of stimulus dimensions. Interference between dimensions is indicated by a drop in performance between an orthogonal condition (two dimensions varied independently) and a control condition (one dimension held constant, the other varied). In a meta-analysis, the ubiquity of Garner interference was examined to understand better the meaning of interference and the theoretical claims that can be drawn from it. Within this context, a set of experiments revisited the source of interference found between talker and phonetic dimensions (Mullennix and Pisoni, 1990). Individual speaker variability (simulated by multiple single-speaker tokens) and word-initial consonant (/b/ vs /p/) were manipulated.
Laughter: Perceptual evaluations of laugh sounds with known acoustic variability
Authors: Bachorowski Jo-Anne , Owren Michael
Published: July 2002

Acoustic analysis of laughter recorded under controlled social contexts revealed significant variability on a number of source- and filter-related acoustic measures. Here, the results of three experiments used to test listeners’ (n=84) evaluations of this acoustic variability are described. The 80 laugh stimuli used in each experiment were selected on the basis of laugher sex, percentage of voicing, F0 contour, and overall laugh duration. Listeners evaluated each stimulus twice using one of three 4-point rating schemes (goodness for inclusion in a laugh track, sincerity, and the extent of positive emotional responding). The results indicate that listeners prefer laughs with voiced, song-like qualities, and suggest that particular patterns of acoustic features in this nonlinguistic human vocal signal are more likely to engender positive emotional responses in listeners. Further analyses will examine the links between listener evaluations, variation in laugh vowel sounds, and acoustic correlates of laugher body size. [Work supported by NSF.]
Race car trajectory determination by multi-source acoustic emission analysis
Authors: Barga Matthew , Guezennec Yann G. , Rizzoni Giorgio
Published: July 2002

This talk presents a signal processing methodology to extract racecar trajectory and engine speed information from a multiple microphone array placed at track side. Phase differences, as well as Doppler shifts of the engine acoustic emissions from an array of microphones, provide multiple sources from which a robust determination of the vehicle trajectory can be extracted. Furthermore, time-frequency analysis of the Doppler-corrected signals provide a rich source of information about the instantaneous engine speed. The combination of both methods provides valuable information about the vehicle and engine characteristics. The analysis method used in this work is applied to acoustic emission data recorded by a track-side array of four microphones. The data analyzed include synthetic validation and calibration data, as well as actual race data. Special attention was devoted to optimizing the microphone array configuration for maximum resolution given an array size. By carefully exploiting the inherent redundancies in the data, a robust and computationally efficient analysis method was successfully developed. The results demonstrate that valuable vehicle and engine parameters can be extracted from such an approach.
An overview of the development for classroom acoustics guidelines
Authors: Nixon Mike
Published: July 2002

This is an overview of past, current and future events that will impact the development of federal acoustical guidelines in classrooms and other facilities in the USA. In 1996 the late Buzz Towne presented clear and compelling evidence to the ASA membership of the need for a greater focus on classroom acoustics. Since that time great progress has been made to reduce acoustical barriers to more effective learning. The TCAA subcommittee on Classroom Acoustics, convened in 1996, opened a path of interdisciplinary communication and cooperation that resulted in the formation of a multidisciplinary ASA Taskforce to further the agenda. In 1997 and 1999 two highly successful interdisciplinary workshops were held in Los Angeles and New York. In 1998 ASA, in collaboration with other professional organizations, mounted a formal response to the US Access Board’s Request For Information on Classroom Acoustics. In March 1999 the Access Board proposed a Course Of Action that resulted in a request to ANSI to develop acoustical guidelines for classrooms within two years. The ANSI approved S12 W/G-42 committee is already working on the development of acoustical standards. Beyond this current task, additional standards may be considered for other facilities.
Chords as spectra; harmony as timbre
Authors: Vassilakis Pantelis N.
Published: July 2002

Traditionally, musical chords have been understood as combinations of discrete tones or as the layering of intervals. From the listener’s point of view, however, chords often fuse into a single perceptual unit with a specific, readily recognized character (i.e., major/minor.) When chordal fusion occurs, a chord’s distinct character can be understood as its timbre in terms of a single inharmonic spectral distribution, rather than a combination of discrete harmonic spectra. The present study examines the relationship between spectral distribution described in terms of (i) spectral centroid (center of amplitude-weighted frequency distribution); (ii) spectral bandwidth (spread of frequency distribution); (iii) spectral density (average number of components per critical band); and (iv) spectral inharmonicity (defined in terms of sensory consonance/dissonance curves) — and perceptual identity of complex tone combinations. It addresses the perceptual equivalence of chord inversions (root, first, second inversion of a single chord category) and the perceptual difference between different chord categories (major/minor) in terms of spectral inharmonicity rather than interval layering. Preliminary results suggest that this study can be extended to examine harmonic motion as a motion between spectral distributions with various degrees of sensory consonance/dissonance, rather than melodic motion between leading tones. [Work supported by UCLA, Graduate Division.]
Acoustic diffraction by a half plane in a viscous medium
Authors: Pierce Allan D. , Nagem Raymond J. , Zampolli Mario
Published: July 2002

A formal solution for the diffraction of sound by a half plane in a viscous medium is given and the special case of plane wave diffraction is implemented and compared to previous results. The acoustic field can be represented as a superposition of acoustic and vorticity modal fields. The two fields satisfy Helmholtz type wave equations and coupled boundary conditions on the surface of the scatterer, requiring that the fluid velocity be identically zero on the surface of the scatterer. The equations are solved by means of the Wiener–Hopf method and integral expressions for the scattered fields are given. The solutions near the edge for the particular case of an incident plane wave are expressed in terms of Fresnel integrals of complex argument. From the solutions it follows that in the vicinity of the edge there exists a boundary layer in which the fluid velocity field has no singularity. The modal components of the velocity field have square root singularities at the edge which cancel out when the two modes add to give the total fluid velocity. Outside the boundary layer the acoustic mode dominates and the solution coincides with the classical inviscid solution.
A modal analysis of the interaction of acoustical signals from submerged fluid-filled elastic shells
Authors: Werby M. F.
Published: July 2002

To most easily identify vibrational components in target-sound scatter, an acoustical background is desirable. Here a new background for fluid-filled elastic structures is subtracted in a coherent manner which leads to a very interesting picture of what happens in such interactions. What is shown is that the results of such scatter yield the coherent effect of the elastic vibrations, the rescatter from within the shell containing the water, but surprisingly there is a proliferation of water-borne waves distributed among all modes as demonstrated in this analysis of the residual modal terms. These ‘‘water-borne’’ modes are well defined, fairly narrow, and evenly displaced. A time domain picture ought to be of interest in further analysis. [Work supported by the Office of Naval Research and Naval Research Laboratory.]
Using phase space diagrams to interpret multiple frequency drive sonoluminescence
Authors: Ketterling Jeffrey A. , Apfel Robert E.
Published: July 2002

The recent experimental results of J. Holzfuss, M. Rüggeberg, and R. Mettin [Phys. Rev. Lett. 81, 1961 (1998)] in which a second harmonic drive system was used to generate sonoluminescence (SL) have been analyzed in the context of the dissociation hypothesis (DH) of D. Lohse and S. Hilgenfeldt [J. Chem. Phys. 107, 6986 (1997)]. The second harmonic introduces two more variables that are under experimental control: a phase and an additional pressure term to the acoustic drive pressure. Diffusive equilibrium curves for a fixed gas concentration were calculated as was the Mach criterion. A phase space diagram was constructed to permit the prediction of regions of stable SL, unstable SL, stable non-SL, and unstable non-SL. These were compared to Holzfuss’ experimental observations, and excellent quantitative agreement was seen. The results provide further evidence that the underlying assumptions of DH are sound. They also indicate the utility of DH for determining appropriate experimental conditions to achieve SL and for optimizing an experimental system.
Modeling the response of acoustically levitated foam drops
Authors: Holt R. Glynn , McDaniel J. Gregory , Akhatov Iskander Sh.
Published: July 2002

Small samples of aqueous foam (‘‘foam drops’’) can be acoustically levitated and manipulated for purposes of investigating their rheological properties [Holt et al., J. Acoust. Soc. Am. 105, 1146 (1999)]. We report here advances in the effort to model the response of foam drops to static and time-varying modulation of the acoustic field to extract rheological properties: the yield stress, the bulk viscoelastic shear and dilatational moduli (complex), and the effective bulk shear and dilatational viscosity numbers. We have begun to develop a bubble-based model of foam mechanics which incorporates the effects of the acoustic field and individual bubble oscillations. Such a model represents a significant advance over traditional models of foam rheology. [Work supported by NASA and NRC.]
Sports acoustics: A simple acoustic method for player performance evaluation during volleyball games
Authors: Browning David G.
Published: July 2002

When struck, a volleyball resonates resulting in an acoustic signal with a frequency of approximately 200 Hz [D. G. Browning et al., J. Acoust. Soc. Am. 97, 3399 (1995)]. By modifying a small, battery-powered, hand-held, sound level meter to receive only in the 125–250 Hz band (now called a SMACKMETER), this sound could easily be monitored from the stands or sidelines. No significant crowd or other noise was encountered in this frequency band during games. It was found that on the university level of womens’ competition, signals varied approximately 10 dB from a soft serve to a hard spike; for high school games the range was less in most cases. It appears to offer a coach or fan a small, economical device to evaluate one aspect of player performance, specifically how hard they strike the ball, during games and warm-ups.