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Acoustics Research Letters Online

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Oct 2004

Volume 5, Issue 4, pp. 125-169

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Formant detail needed for vowel identification

Amy T. Neel

ARLO Volume 5, Issue 4, pp. 125-131 (June 2004); (7 pages) | Cited 3 times

Online Publication Date: 25 Jun 2004

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Changes in formant frequency over time are important for vowel identification: listeners identify stimuli containing time-varying formants better than stimuli with steady-state formants. Statistically based pattern classifiers used as models for human perception have shown that very coarse representations of formant change over time result in accurate classification of American English vowels. In this study, using synthetic stimuli with five levels of formant contour detail, human listeners achieved maximum vowel identification for relatively coarse representations of formant movement containing information about onset, offset, and midpoint frequencies. More detailed representations of contour did not improve identification for most vowels. © 2004 Acoustical Society of America.
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43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
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Effects of visual gender and frequency shifts on vowel category judgments

Catherine M. Glidden and Peter F. Assmann

ARLO Volume 5, Issue 4, pp. 132-138 (June 2004); (7 pages) | Cited 2 times

Online Publication Date: 30 Jun 2004

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Visual morphing and a high-quality vocoder were used to study the audio-visual contribution of talker gender to the identification of frequency-shifted vowels. Several acoustic continua from “bit” to “bet” were generated incorporating fundamental frequency (F0) and spectral envelope shifts. Visual continua were constructed from male or female faces, and corresponding steps along the audio/visual continua were synchronized. Boundary shifts emerged for both acoustic cues (F0 and spectral envelope shifts) and visual cues (visual gender) as predicted by the co-variation of these properties in natural speech. Results suggest that perceivers exploit learned relationships between acoustic and visual cues when judging vowel identity. © 2004 Acoustical Society of America.
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43.71.Es Vowel and consonant perception; perception of words, sentences, and fluent speech
43.71.Rt Sensory mechanisms in speech perception
43.71.An Models and theories of speech perception
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Investigation into the uniqueness of neonate transient otoacoustic emissions

Matthew A. Swabey, Stephen P. Beeby, Andrew D. Brown, and John E. Chad

ARLO Volume 5, Issue 4, pp. 139-142 (July 2004); (4 pages)

Online Publication Date: 09 Jul 2004

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This work presents initial findings from an investigation into the use of otoacoustic emissions (OAEs) for identifying individuals. A data set of 2009 neonate transient otoacoustic emissions was quantified for uniqueness using the Euclidean distance separation of the power spectra. Each sample was compared to all the others and the minimum separation recorded. The percentage separation for 50%, 95%, and 99% of the sample set was calculated and the distribution of the minimum separation plotted. The minimum separation between samples was 1.84% while 99% of the samples had a separation of 3.68%. A simple technique was able to achieve a separation of 3.68% for 99% of the data set, indicating it is highly likely that otoacoustic emissions are unique to an individual and of potential use as a biometric variable in an identification system. © 2004 Acoustical Society of America.
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43.64.Jb Otoacoustic emissions
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Comparison of group delays of 2f1−f2 distortion product otoacoustic emissions and cochlear travel times

Mario A. Ruggero

ARLO Volume 5, Issue 4, pp. 143-147 (July 2004); (5 pages) | Cited 18 times

Online Publication Date: 14 Jul 2004

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To help elucidate how distortion-product otoacoustic emissions propagate from their cochlear sites of origin to the middle ear, their group delays were compared with basilar-membrane and organ of Corti travel times measured in guinea pig, gerbil, and chinchilla. © 2004 Acoustical Society of America.
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43.64.Jb Otoacoustic emissions
43.64.Kc Cochlear mechanics
43.64.Bt Models and theories of the auditory system
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Detecting large particles in a slurry by measuring acoustic cavitation thresholds

Sameer I. Madanshetty and Hang Ji

ARLO Volume 5, Issue 4, pp. 148-152 (August 2004); (5 pages) | Cited 1 time

Online Publication Date: 05 Aug 2004

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Acoustic microcavitation is used to detect particles in liquids and suspensions. The observation that an acoustic cavitation threshold is characteristic of particle size is exploited to develop a solution for an important problem facing chemical mechanical planarization of silicon wafers. Specifically, it is established via experiments that a sparse presence of large particles in a nanofine slurry can be detected acoustically. Being able to detect such large particles prior to chemical mechanical planarization polishing is expected to save the wafers from being scratched during planarization. The acoustic method is entirely noninvasive. © 2004 Acoustical Society of America.
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43.35.Ei Acoustic cavitation in liquids
43.35.Zc Use of ultrasonics in nondestructive testing, industrial processes, and industrial products
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Limitations of theoretical benefit from an adaptive directional system in reverberant environments

William S. Woods and Timothy D. Trine

ARLO Volume 5, Issue 4, pp. 153-157 (August 2004); (5 pages) | Cited 2 times

Online Publication Date: 13 Aug 2004

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Hearing aids with adaptive and fixed two-microphone processing are currently available. Although the noise reduction increase of adaptive over fixed aids can theoretically be tens of dB, it is unclear if this benefit can be found with realistic processing and conditions. Thus, a theoretical analysis of the ability of today’s aids to attenuate jammers in “everyday” conditions [direct-reverberant ratio ⩽ 5.0 dB] is provided. Processing limitations restrict aids to wideband null steering through intermicrophone delay variation. Delay variation is predicted to provide maximally 2.0 dB more noise reduction than the best fixed system on average, and only at the highest direct-reverberant ratios.© 2004 Acoustical Society of America.
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43.66.Ts Auditory prostheses, hearing aids
43.72.-p Speech processing and communication systems
43.38.Hz Transducer arrays, acoustic interaction effects in arrays
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International Round Robin on Room Acoustical Impulse Response Analysis Software 2004

Brian F. G. Katz

ARLO Volume 5, Issue 4, pp. 158-164 (August 2004); (7 pages)

Online Publication Date: 23 Aug 2004

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The intent of this study is to examine the variations between current implementations of standard room acoustic measures for impulse response measurements. An international round robin has been conducted using a single real measured impulse response, rather than a synthesized response. This offers a more rigorous test of analysis procedures. While there is good agreement at higher frequencies, large variations are found at lower frequencies in which the noise level within the measurement is greater. Some errors are attributed to the existence or robustness of noise-floor detection. © 2004 Acoustical Society of America.
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43.55.Mc Room acoustics measuring instruments, computer measurement of room properties
43.58.-e Acoustical measurements and instrumentation
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Imaging the destruction of individual ultrasound contrast microbubbles with diagnostic ultrasound

Jingfeng Guan, Thomas J. Matula, and Michalakis Averkiou

ARLO Volume 5, Issue 4, pp. 165-169 (September 2004); (5 pages) | Cited 5 times

Online Publication Date: 15 Sep 2004

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Ultrasound imaging of ultrasound contrast agent fragmentation in a water bath was performed with the color Doppler mode of the HDI 5000 (Phillips Ultrasound). A highly diluted suspension of ultrasound contrast microbubbles (Optison®) was injected into the water bath such that individual microbubbles passed through the image plane every few seconds. Decorrelation of the signal, along with the appearance of multiple signals, suggests that single microbubble fragmentation was observed, with daughter bubbles being formed from the original microbubbles, depending on the applied acoustic pressure. © 2004 Acoustical Society of America.
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43.35.Ei Acoustic cavitation in liquids
43.80.Qf Medical diagnosis with acoustics
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