bluuebunny/crossref_metadata_2025 huggingface dataset:
Lexical stress and its application in large vocabulary speech recognition
Authors: Aull Ann Marie , Zue Victor W.
Published: October 2005

Recent research (Huttenlocher and Zue, ICASSP 84) indicates that segmental information for isolated words provides strong constraints for lexical access. Furthermore, the results suggest that the lexical constraints provided by segments around stressed syllables are stronger than that around unstressed syllables. The present study focuses on two related issues. First, we investigate the amount of lexical constraint provided by stress information alone. Second, we implement a system that derives the stress information from the acoustic signal. In order to determine the lexical constraints provided by stress information, the polysyllabic words in the Merriam pocket dictionary are mapped into their corresponding stress patterns. The results indicate that, from stress information alone, the largest class size constitutes 28% of the lexicon. An overall expected class size of 15% illustrates the constraining power of the stress information. In order to exploit these findings, we develop a system that determines the stress pattern of isolated words and performs subsequent lexical access. The system initially segments the speech signal into broad phonetic classes. From these segments, syllable nuclei are determined. Next, known acoustic correlates of stress, such as duration, energy, and fundamental frequency, are extracted for each syllable. The stress pattern is established through a relative comparison of the syllable feature vectors. Finally, lexical access based on the derived stress pattern provides a list of word candidates. Phonological rules are incorporated to account for variations in the number of syllables from the lexical base forms. The system is evaluated on a database of 1500 isolated words, spoken by eight speakers, with varying degrees of difficulty for syllabification. Preliminary evaluation suggests that the majority of error can be attributed to initial segmentation and syllabification. Less than 5% is due to the stress algorithm. [Work supported by the Office of Naval Research under contract N00014-82-K-0727 and by the System Development Foundation.]
A model of temporal processing in cochlear implants
Authors: Shannon Robert V.
Published: October 2005

Some psychophysical measures of temporal processing in cochlear implant patients are similar to normals but others are not [R. V. Shannon, Hear. Res. 11, 157–189 (1983)]. Forward masking in implants appears to have a slightly longer time course than acoustic forward masking. Gap detection thresholds and temporal integration in implants appear to be shorter than the same measures with acoustic stimulation. This does not necessarily mean that the temporal mechanism is different or more impaired in implant patients than in normals. The differences can be described by a new model based on an earlier model by Zwislocki [J. J. Zwislocki, J. Acoust. Soc. Am. 46, 431–441 (1969)]. The differences in temporal measures could be due to the steep loudness versus intensity function observed in implants. This function, followed by normal temporal processing, would yield apparent changes in temporal measures that are in line with the observed implant results. Electrical stimuli could be preprocessed so that the resultant temporal measures would be normal. [Work supported by NIH.]
Relationships between speech understanding and temporal processing abilities in cochlear implant patients
Authors: Hochmair-Desoyer Ingeborg J. , Stiglbrunner Helmut K. , Wallenberg Ernst-Ludwig
Published: October 2005

A battery of tests has been used with the 20 postlingually deafened patients who have received a Vienna Cochlear Implant in Vienna and have had their implant for at least 3 months. The battery included tests determining the temporal difference limen for a 250–1000-Hz and a 2000–4000-Hz noise signal, gap detection tests using the same two signals and a periodic/aperiodic discrimination test. The speech tests were open set one-syllable-word understanding, open set sentence understanding, a 16-consonant identification, and an eight-vowel identification. The four speech tests were performed without lipreading. For all temporal processing ability tests, limits could be found which separated those 75% of the patients who were able to understand single-syllable words and sentences to a varying degree and those who were not. Correlations between the speech tests, except the vowel test, and the tests for temporal processing abilities could be found. These correlations demonstrate that cochlear implant patients wearing an analog broadband single-channel sound processor have to rely heavily on their ability for temporal processing. [Work supported by the Austrian Research Fund.]
An analysis of consonant confusions by single-channel cochlear implant users
Authors: Dent L. J. , Huntington D. A. , Schubert E. D. , Simmons F. B. , White R. L.
Published: October 2005

Four cochlear implant subjects fitted with single-channel sound processors identified consonants taken from a 23-consonant set and spoken in a VCV context. The videotaped VCV items were presented in three conditions: lipreading alone, stimulation alone, and stimulation plus lipreading. The subjects had had no training or testing with VCVs prior to the tests reported here. Tests were conducted within the first 0–8 months of the first fitting of the wearable single-channel processor. A total of 7590 identifications were collected and analyzed. All subjects scored near 30% correct in the lipreading alone condition, but 3%–12% correct (near chance) in the stimulation alone condition. A broader range of scores obtained when stimulation was added to lipreading (30%–55% correct). Errors were classified in terms of three features: voicing, and place and manner of articulation. Detailed scrutiny of the error profiles indicates that beyond improving the overall percent correct identification, the addition of stimulation to lipreading allows subjects to make fewer two- and three-feature confusions, narrowing down the choice of alternatives to those that differ by a single feature. [Work supported by NIH.]
A selective review of the psychophysics of intensity discrimination
Authors: Viemeister Neal F.
Published: October 2005

Intensity discrimination is a topic of long-standing interest in audition because it reflects processes which are fundamental to auditory perception. This paper reviews the basic psychophysical phenomena of intensity discrimination and focuses on those aspects which appear most relevant to possible mechanisms by which intensity is coded at the periphery. Of special concern is the contrast between the enormous dynamic range shown in intensity discrimination and the typically limited dynamic range of single fibers in the the auditory nerve “bottleneck.” [Supported by NINCDS grant NS12125.]
Measurements of sound transmission loss with a two-microphone sound intensity analyzer
Authors: Walker Keith W.
Published: October 2005

Four practical experiments were devised to assess the usefulness of a Bruel & Kjaer sound intensity analyzing system for general purpose sound transmission loss tests. The first experiment was conducted between two offices built under a suspended acoustical ceiling. The second was on a drywall partition installed between two reverberant rooms; it was known that little sound energy would bypass the test specimen in this setup. The third was on a similar drywall partition between two reverberant rooms, except that a significant quantity of sound energy was permitted to bypass the test specimen. Finally, an experiment was conducted to determine if the analyzer could identify areas of missing sound absorbing blankets in a demountable office partition. Three of the experiments were successful. In particular, the third experiment demonstrated a capability for measuring TL values even in the presence of flanking sound which bypassed the test partition at a level up to 20 dB above that transmitted directly through the partition. [Sound intensity analyzer loaned by Bruel & Kjaer Instruments, Inc.]
Transmission loss measurements: Conventional versus intensity
Authors: Halliwell R. E. , Warnock A. C. C.
Published: October 2005

A two-room reverberation suite with rooms of different volume was used to compare transmission loss measurements made using conventional methods with those made using the intensity method. The rooms are connected by a “tunnel” 1.4 m long, in which the specimen was placed at five different locations. Conventional transmission loss measurements were made in both directions and intensity measurements made with the small room acting as the receiving room. To simulate the wide range of receiving rooms found in read buildings and to test the sensitivity of the intensity method to reactive fields, four different absorption conditions were presented in the small room for each of the wall positions. Neither method was found to vary appreciably with the amount of absorption, but both showed dependence on the wall position. The intensity method was found to give a transmission loss much closer to the expected mass law dependence than did the conventional method.
Using sound intensity measurements to determine room corrections
Authors: Alexander M. , Peppin R. J. , Guernsey R. M. , Hedeen R. A.
Published: October 2005

An alternative to the classic reverberation-time measurements for determination of sound absorption coefficients (ASTM C423) is the steady-state method which measures the energy average sound pressure level of a reference source (of known sound power) with and without a sample in a reverberation room. In addition, sound power measurements in reverberant rooms require the use of a reference source to determine the room corrections. To successfully use these techniques, sound power must be known with great accuracy. With the advent of sophisticated sound intensity instrumentation, it becomes very easy to determine sound power in almost any type of space. In this paper, the authors report the use of sound intensity to test several reference sound sources in various environments, including reverberant, hemi-anechoic, and semi-diffuse, to determine the changes in measured sound output. In addition, the reference sources' emissions are compared with manufacturers' specifications based on techniques similar to S12.5, and intensity techniques. The differences among results for the sources/spaces/techniques will be discussed.
An analytical investigation of sound intensity measurements in a reactive environment
Authors: Thompson James K. , Huynh Than
Published: October 2005

The two-microphone method for measuring sound intensity has been touted as an important new technique for source analysis. One of the major advantages cited for this technique over traditional pressure measurements is its ability to make measurements in situ without the need for special test chambers. However, many investigators have encountered difficulties in using this technique in highly reverberant environments where much noise-producing machinery in industry is located. The inaccuracies found in these studies indicate that the two-microphone technique may not be practical in many industrial environments. An investigation of these errors is presented in this paper. Single and multiple reflecting surfaces are considered for monopole, dipole, and more general sources. Conclusions are drawn as to the ideal limitations of sound intensity measurements in reactive fields. The effects of the various measurement parameters such as microphone separation, measurement distance, angle of incidence on the reflecting surface, and other factors are also considered. These results show that the presence of a reflecting surface can dramatically change the accuracy of intensity measurements. In some instances, measurement errors rose from tenths of a decibel to tens of decibels when a reflecting surface was introduced.
Sonic booms of space shuttles landing at Edwards Air Force Base
Authors: Young Robert W. , Awbrey Frank T.
Published: October 2005

At a place 33 miles westerly of Edwards Air Force Base, we measured the sonic boom of Space Shuttle Orbiter STS-1: a peak flat sound pressure level of 125 dB and a A-weighted sound exposure level of 81 dB. When STS-1 was 33 miles distant it was approaching EAFB at Mach 2.6 at an altitude above ground of about 23 km (75 kft); slant range from STS-1 to the sound measurement position about 25 km. Three miles west of EAFB South Base we measured the sonic boom of Orbiter STS-9: a peak flat sound pressure level of 131 dB (1.4 psf), a flat sound exposure level of 122 dB, an A-weighted sound exposure level of 95 dB. The duration of the N wave was 380 ms. Presumably, the boom was generated by STS-9 decelerating through Mach 1.2, and turning eastward, at an altitude above ground about 16 km (52 kft); slant range south to the sound measurement position was about 28 km (90 kft). We also measured in the vicinity of EAFB for STS-2, STS-4, STS-5, STS-6, STS-7, and STS-8. Dc-to-5-kHz recordings of the later booms provide data, with absolute calibration, for waveforms and (1-Hz band) spectra of sound exposure spectrum level. A-weighted and C-weighted sound exposure levels are derived from the wideband recordings.
The velocity distribution on a sinusoidal surface—exact versus the Kirchhoff approximation
Authors: McCammon Diana F.
Published: October 2005

Using an exact solution for scatter from a pressure release sinusoidal surface, the unknown surface velocity distribution from plane-wave excitation can be computed. Comparisons are presented between this solution and the velocity distribution predicted by the Kirchhoff approximation (both with and without consideration of shadowing) with grazing angle as a parameter. The effects of surface shadowing are shown and the nature of the difference between the solutions is investigated. Surprisingly, the Kirchhoff approximation gives good results for the reflection coefficient at very low grazing angles; however, the reason for this agreement is fortuitous. A diffractive shadowing correction to be the Kirchhoff approximation is examined and is shown to yield little improvement.
Acoustic scattering from the sea surface
Authors: Koenigs Paul D. , Monti Joseph M. , Nuetzel Bernd , Herwig Heinz
Published: October 2005

The results of an experiment designed to measure the forward and backward scattering strength of acoustic energy from sea surfaces are presented along with supporting surface roughness parameters. The acoustic data were obtained using a bottom-mounted high resolution parametric sonar transmitter and conventional receivers in the shallow waters of the North Sea. Scattering strength values were obtained as a function of frequency (3–20 kHz) and grazing angle (90°–15°) over a limited set of environmental conditions. The mean forward and backward scattering strength values exhibited little dependence on frequency but a clear dependence on surface roughness. The coefficient of variation for these data clearly approaches a minimum value at the specular angles. Comparisons with theoretical and semi-empirical models indicate the appropriateness of using composite roughness modeling theories. [Work supported by NAVSEA.]
Acoustic scattering from the seafloor
Authors: Monti Joseph M. , Nuetzel Bernd
Published: October 2005

Acoustic bottom backscattering strength measurement results from an experiment conducted in the shallow waters of the North Sea are presented. The data were obtained using a bottom-mounted high resolution (narrow beamwidth) pulsed parametric sonar transmitter and conventional receiver. Scattering strength values were obtained as a function of frequency (3–20 kHz) and azimuth (100° sector) at a grazing angle of 9°. The average scattering strength values are dependent on frequency and exhibit little azimuthal dependence. Instantaneous scattering strength values obtained from point scatters within the insonified area of interest exhibit a high degree of frequency and azimuthal dependence. The data are found to be reasonably consistent with the experimental data of Urick, and Bunchuk and Zhitkovskii [Sov. Phys. Acoust. 26(5)(Sept.-Oct. 1980).] [Work supported by NAVSEA.]
Scale modeling in architectural acoustics
Authors: Kahn David W. , Tichy Jiri
Published: October 2005

Several types of models are available to the acoustician for the study of room acoustics. Although mathematical modeling has now become popular, due to recent advances in computer technology, the author chose to use scale modeling techniques. A 1:10 scale model was constructed to study the sound field above the audience in a large lecture hall. A steady-state jet sound source was developed to model the standard ILG reference sound source. A model of unoccupied audience seating was designed and constructed and a new approach to air absorption compensation was used. A data acquisition procedure was developed for easy and accurate comparison of data taken in both the model and the full-scale lecture hall. Verification of the model was carried out with measurements of both reverberation time and steady-state sound levels. This scale model continues to provide a useful tool for the study of sound propagation over audience seating. It also enables simple modifications to determine the dependence of the reverberant field on both the magnitude and placement of absorption within the enclosure.
Audible simulation using scale model impulse responses
Authors: Essert Robert D. , Walsh John P. , Edwards Nicholas , Cormack Randy
Published: October 2005

Acoustical responses acquired in a scale model have been used to produce audible simulations for subjective evaluation of architectural conditions. A spark source excites the model, and the response of a miniature microphone is sampled by a microcomputer-based data acquisition system. The model response so obtained is deconvolved by using “pseudo-SVD” pseudoinverse filtering developed by Walsh and Ulrych. This deconvolution technique circumvents, in an optimal manner, the “whitening” effect of previously available methods. The resulting impulse response is reconvolved with anechoically recorded music to yield an audible simulation of the conditions being investigated. As an example, the use of this technique in the acoustical design of a concert hall is discussed. Here a 1:24 scale model was used in the study of the subjective effect of diffraction from a large architectural grille. The early portions of the model impulse responses collected with and without the grille were convolved with anechoically recorded music. Comparison of these audibly demonstrated the coloration introduced by the grille.
Acoustic correlates of aging
Authors: Ramig Lorraine A. , Scherer Ronald C. , Titze Ingo R.
Published: October 2005

Speaker age may be an important variable in the assessment of normal and pathological voices as well as in voice identification and recognition. It is therefore necessary to determine acoustic variables which predict not only chronological age of speakers but also listeners' perception of speaker age. Auditory and acoustic studies were carried out on vowel productions of 48 subjects, aged 25–75 years, and representing good and poor levels of physiological condition [L A. Ramig and R. L. Ringel, J. Speech Hear. Res. 26, 22–30 (1983)]. Results indicate that age could be predicted only in the poor physiological condition group. Acoustical analyses, including GLIMPES [I. R. Titze, J. Acoust. Soc. Am. 75, 570–580 (1984)], derived mean fundamental frequency, intensity, harmonics-to-noise ratio [E. Yumoto, W. J. Gould, and T. Baer, J. Acoust. Soc. Am. 71, 1544–1550 (1982)], amplitude perturbation and period perturbation. Multiple regressions revealed that this set of variables was a significant predictor (p < 0.01) of age ratings. Implications regarding acoustic measures related to listeners perception of aging and associated laryngeal characteristics will be discussed. [Work supported in part by NIA.]
Role of intensity discrimination in intensity perception
Authors: Braida L. D. , Durlach N. J. , Rabinowitz W. M.
Published: October 2005

The discrimination of intensity plays a central role in Fechnerian theories of the perception of intensity: Perceptual differences between two stimuli are determined by the cumulative number of jnd's which separate the intensities. We review recent research which suggests that this view must be modified to account for the total number of jnd's in the listener's dynamic range or in the range of intensities used in an experiment. Specifically, loudness balance measurements are better predicted if the number of jnd's is normalized by the total number of jnd's in the dynamic range. Resolution between two intensities in identification experiments reflects not only the number of jnd's separating the intensities, but also the total number of jnd's in the stimulus range and the proximity of the intensities to perceptual anchors. These results indicate the need for complementing our increasing understanding of intensity discrimination with an improved understanding of perceptual anchors and the limits of the dynamic range.
The perception of continuity in interrupted tone signals by hearing-impaired listeners
Authors: de Laat J. A. P. M. , Plomp R.
Published: October 2005

Hearing-impaired listeners have problems in understanding speech, especially in noisy conditions. Since speech is a fluctuating signal, it is of interest to investigate the relation between the perception of speech and of stimuli fluctuating in time. We measured the continuity threshold for bursts of pure tones alternated with noise bursts [denoted as the pulsation threshold by Houtgast (thesis, Amsterdam, 1974)] in a group of 20 hearing-impaired and 10 normal-hearing subjects. The tone-noise period varied from 100 to 800 ms and the tone level from 10 to 80 dB above hearing threshold. A special measuring technique made it possible to obtain highly consistent and reliable results. The results show that there is an effect of fusion of discontinuous signals. For the normal-hearing subjects the continuity threshold drops to lower tone-burst levels for longer tone-noise periods. For the hearing-impaired listeners this phenomenon is even stronger. The range of the transition between the perception of continuity and of discontinuity is larger for the hearing-impaired than for the normal-hearing listeners. We also found some relations with other auditory functions measured. [Work supported by ZWO.]
Downward spread of masking and low-frequency hearing loss
Authors: Collins M. J. , Yanda J. L. , Fryauf H. , Schum D. J.
Published: October 2005

The effectiveness of high-frequency noise for masking lower frequency pure tones was measured for hearing-impaired subjects exhibiting rising audiometric contours. The subjects differed with respect to the frequency range over which their hearing was most sensitive and the degree of low-frequency loss. Maskers were either narrow bands of noise centered at the listener's best frequency or broader bands of noise which filled the region of best hearing. Comparative data were collected on naive, normal hearing listeners. The results indicate that large individual differences exist in the degree to which abnormal downward spread of masking is evident for persons with low-frequency hearing loss. Apparent in the data is the complexity of the relationship between the slope of the rising portion of the audiogram, the bandwidth of the masker, the extent and location of the frequency range of best hearing, and the frequency of the probe tone. The interactive effects observed account for conflicting evidence in the literature as to the validity of the argument that artifactual responses to low-frequency signals are obtained in routine audiometric procedures on this population of hearing-impaired individuals. [Work supported by DRF.]
Light scattering from acoustically levitated spheroidal drops: Discovery of a new hyperbolic umbilic diffraction catastrophe
Authors: Marston Philip L. , Trinh Eugene H.
Published: October 2005

There has been recent progress in understanding the scattering patterns from penetrable spheroids at long wavelengths. At short wavelengths, however, partial-wave sums are difficult to evaluate, while geometric optics is not applicable near angular loci where the scattering is enhanced. Consequently, the discovery and classification of angular foci is important to the understanding of short wavelength scattering. Our observation of a new focus or “diffraction catastrophe” in scattering from an oblate drop of water in air used an acoustic standing wave to levitate the drop and control its shape. The drop was illuminated by a horizontally propagating laser beam and its symmetry axis was vertical. The farfield scattering pattern was observed near the rainbow region. The two-dimensional pattern was recognized to be that of a hyperbolic umbilic diffraction catastrophe, known because of other applications [M. V. Berry and C. Upstill, Prog. Opt. 18, 257–346 (1980)]. Changing the drop's aspect ratio corresponds to varying the “control parameter” C3. Strong focusing with C3 = 0 was observed. [P. Marston was supported in part by JPL and ONR.]
Diffraction pattern in a fluid loading a vibrating plate
Authors: Waterhouse R. V. , Archibald F. S.
Published: October 2005

At the last meeting, some results were given for the power scattered by a fixed point on an infinite fluid-loaded plate, when rectilinear waves are incident. Graphs obtained by the use of the thin-plate theory were given for the scattered power (a) in the plate, and (b) in the fluid, as functions of frequency. Here the sound field in the fluid adjacent to the plate is analyzed. The pressure at an arbitrary field point is given by a transform integral, and charts of pressure contours have been computed for the nearfield by evaluating large numbers of these integrals numerically. Comparison is made with the cases where the plate is excited by (a) rectilinear waves alone, and (b) circular waves alone.
The breakdown of the Green's function eigenvulue expansion in finite element analysis near a source
Authors: Geddes Earl , Porter James
Published: October 2005

A finite element analysis solution for the normal modes in a rectangular room characterized by a small patch of highly absorptive material on one wall was performed. The authors' previous results for this problem indicated a nonphysical falloff of the sound intensity near the source [J. Acoust. Soc. Am. Suppl. 1 74, S23 (1983)]. The reason for this falloff has been identified as a result of the truncation of the Green's function eigenvalue expansion required by the finite element method. This paper shows that this behavior can be overcome (to a large extent) by performing certain algebraic manipulations on the form of the Green's function prior to truncation. The result is an improved rate of convergence of the Green's function, particularly near the source. A more accurate analysis of the energy flow can then be obtained with a limited number of low-frequency modes. Results obtained with this new approach will be compared with those found in the authors previous work.
Sampling rates dominate operations counts for underwater acoustics modeling
Authors: Wood David H.
Published: October 2005

This paper presents some estimates for the computer resources needed for modeling sound fields in the ocean by several types of numerical computer models. The models include a ray model, a normal mode model, a mixed ray and mode model, and both split step and finite difference parabolic equation models. We have also included estimates for some proposed “fast” methods using the fast Fourier transform. For each model, we estimate its sampling rates and its operations count. The sampling rates govern the number and placement of the grid points and the storage requirements. The computation time is more or less proportional to the operations count. Operations counts actually express fundamental limitations, rather than precise running times. Different models with the same operations counts may differ greatly in their running time. The operations counts will always make a dramatic difference in running time for large enough problems. However, in typical applications it is the sampling rates that dominate comparisons of models. The crucial issue is whether the model must sample over wavelengths or merely over dimensions characteristic of the variations of the ocean. Since the typical horizontal variation is of the order of a thousand wavelengths, any three-dimensional model that samples horizontally over characteristic distances will start off with about a million-to-one advantage over a model that samples in wavelengths.
Effect of directivity on the sound field produced by a source above a reflecting plane
Authors: Moreland J. B.
Published: October 2005

In describing equipment sound emissions, it is desired to measure its noise radiation spectra with the equipment located in an anechoic or reflection-free environment. In practice, however, there are a number of situations where sound measurements are made with the equipment in hemi-anechoic space, in which case the equipment is located on a reflecting plane, but in an otherwise reflection-free environment. One problem associated with measurements made in hemi-anechoic environments is that the sound spectra measured under these conditions are not necessarily the same as the spectra that would be produced by the source in the absence of the reflecting plane. Investigators have sought to reconstruct the spectra that would be measured in anechoic space from measurements of spectra made with the source in a hemi-anechoic environment by assuming the equipment to be a point source located above a reflecting plane. In this paper, we examine the effect of directivity on measurements made in a hemi-anechoic environment by computing and measuring the sound field produced by a collinear array of five point sources. Our results show that source directivity has a considerable effect on the radiated sound pressure levels. Finally, the maximum sound pressure levels occur when the major lobe in the source directivity is directed toward the reflecting plane.
Effects of amplitude (AM) and phase modulation (PM) on the coherence of rotating sources
Authors: Yeager David M.
Published: October 2005

Noise source identification in turbomachinery often requires estimation of the correlation between multiple rotating (aerodynamic) sources and the stationary radiated sound field. When treated as a multiple input/output problem, relative motion between input (sources) and output signals has the effect of amplitude and phase, modulating the input. The resulting nonlinearities introduced into the system affect the estimation of the coherence function. A straightforward approach will be used to examine the AM and PM effects as they pertain to the multiple input/output model for rotating sources. As pointed out in the literature on rotating diffuser models [Elko, M.S. thesis, Pennsylvania State University (1980)], source directivity plays a significant role in determining the strength of the AM spectra. This point is best illustrated by comparing the results of rotating monopoles and dipoles, and extrapolating these results to other radiation patterns. The consequences of PM are viewed through the general Doppler formula, applied to the specific geometry of rotating sources in an arbitrary plane with respect to a fixed observer. The possibility of removing the AM/PM effects by prepossessing the signals will also be discussed.
Modal analysis used to visualize the acoustic response of a pump
Authors: Kendig R. P.
Published: October 2005

An air model is used to investigate potentially damaging pulsation responses of a pump. The internal cavity responses in an air model of the pump are determined. The methods commonly used in vibration modal analysis are applied to determine the acoustic modes of oscillation. This technique determines the internal response by exciting a volume of air inside the pump and proving its interior with two small microphones. Linear transfer functions are then computed and used to visualize some of the natural motion of air in various internal sections of the pump. Standing waves are established in accordance with the geometry of the test facility and the pump and its cavities and channels. The response of the pump interior is partially governed by the impeller and diffuser combination.
Relationships between transient and steady-state AEPs, and AEMFs determined from SQUID measurements
Authors: Klein Alan J. , Tubis Arnold , Jones Kenneth , Burns Edward M.
Published: October 2005

When an auditory stimulus is presented at a repetition rate fr of about 40/s, a robust steady-state auditory evoked potential (AEP) is recordable [R. Galambos et al., Proc. Natl. Acad. Sci. (USA) 78, 2643–2647 (1981)], and has an approximate sinusoidal waveform with frequency fr. A similar phenomenon is encountered when auditory evoked magnetic fields (AEMFs) are measured at the scalp with a SQUID magnetometer. We have determined the fr dependence of the steady-state AEPs and AEMFs for the same human subjects. Using the assumption of a sandwich system (linear transformation-zero memory nonlinear transformation-linear transformation) response, we have also produced computer simulations of the fr dependence of steady-state responses from measured transient-response data. The simulations account fairly well for the steady-state data. The stimulus was a 500-Hz tone pip presented with fr varying from 3-50/s. The AEMF was recorded from a point around the T4 location, and the AEP was recorded between electrodes at CZ and the mastoid process of the test ear. Preliminary results for optimal fr's are 40-45/s for the AEPs and 30-35/s for the AEMFs. [Work supported by NINCDS, NSF, and the Purdue University Biomedical Support Fund.]
Noise exposure in hyperlipidemic chinchillas
Authors: Morisono Tetsuo , Sikora Michael A. , Ward W. Dixon , Paparella Michael M. , Jorgensen Jeffrey L.
Published: October 2005

Two groups of chinchillas were maintained on either a normal diet or a 1% cholesterol diet for 6 months. Auditory Brainstem Response (ABR) measurements were obtained with tone-burst stimuli at 1, 3, 5, and 6 months after initiation of diet. Compound Action Potential measurements were obtained at sacrifice at 6 months. A significant elongation of ABR P 1 latency was observed at 5 months-on-diet but not at 1 and 3 months, in the cholesterol group. No significant change in the normal group's ABR was observed. At 5 months, the animals were exposed to a 2-oct bandpass noise centered at 1 kHz at 105 dB for 220 min. One month following noise approximately half of the cholesterol diet animals exhibited P 1 latency shifts outside the 99% confidence interval of the normal group. AP threshold was elevated at 2–16 kHz in both normal and cholesterol-diet noise-exposed groups compared to the normal-diet non-noise-exposed animals. Of the noise-exposed groups, the cholesterol-diet animals had higher thresholds at the higher frequencies than the normal-diet group. Serum cholestrol and low density lipoprotein levels were significantly higher in the cholesterol-diet group than in the normal-diet group. [Work supported by NIH grant NS-17994.]
Effect of signal phase for two-tone masking as a function of masker separation
Authors: Hanna Thomas E.
Published: October 2005

The detectability of a sinusoid masked by two sinusoids was studied as a function of signal phase and the frequency separation between the maskers and the signal. Masker and signal durations were 400 ms. The signal was arithmetically centered in frequency between the two masker components. Signal frequencies of 1 and 4 kHz, eight signal phases, and 12 values of r = |fm − fs|/fs from 0.005–0.5 were used. An effect of signal phase was evident and was consistent across subjects for r <0.15. For 0.015 <r <0.15, the signal was most detectable at phases of 0° and 180° and was least detectable at phases of 90° and 270°. The effect of signal phase for r<0.015 was different from that for 0.015 <r <0.15. The results will be discussed in terms of envelope cues and the interaction of combination tones. [Work supported by NIH.]
The effect of an auditory time constant on time/intensity trading
Authors: Faupel Mark L. , Mulligan B. E.
Published: October 2005

Previous findings [B. E. Mulligan, L. S. Goodman, D. P. Gleisner, and M. L. Faupel, J. Acoust. Soc. Am. (in press)] have indicated a stepwise dependence of binaural loudness on interaural phase for 250-, 500-, 650-, 1000-, 1200-, and 1400-Hz tones presented in “quiet.” The steps in loudness were found to occur at interaural phase angles which correspond to the natural limits of confusion-free zones for tones of these frequencies. In the present research, observers reported the intracranial position of tonal stimuli which were laterally displaced by means of various combinations of interaural phase and intensity imbalances. It was found (for the same frequencies listed above) that the rate at which interaural phase was “traded” against interaural intensity changed abruptly near the limits of the confusion-free zones. In addition, observers encountered greater difficulty in making reliable judgments of image position when phase was shifted near these limits.
Pulsation threshold and simultaneous masking: 2AFC results
Authors: Ayres Thomas J.
Published: October 2005

The pulsation threshold is the signal level at which a series of brief signals appears to be (illusorily) continuous when the intervening intervals are filled with a “masker” (different signal source). It is generally measured by an adjustment or tracking procedure. As a function of the frequency relation of the signal and “masker,” pulsation threshold results are similar in many respects to simultaneous masking patterns. It has been suggested that the two techniques are generally measuring the same aspects of hearing. This was tested by using a 2AFC PEST procedure: pulsation threshold was defined as the signal level for 75% correct discrimination between illusory continuity (signal on only when masker off) and true continuity (signal on at all times). Results were essentially identical to those obtained with a 2AFC PEST simultaneous masking procedure, as well as with a standard tracked pulsation threshold procedure. Given the difficulty which naive subjects often have with finding a stable criterion for pulsation threshold judgments, the 2AFC procedure may be preferable to adjustment tasks. [Work supported by the Deafness Research Foundation.]
Perception of the missing fundamental in a songbird
Authors: Cynx Jeffrey , Hulse Stewart H.
Published: October 2005

Although birdsong is harmonically complex, there is little or no evidence that songbirds are sensitive to the harmonic structures in the same way as humans are. The present experiment was designed to see if starlings (Sturnus vulgaris), a mimicking species of songbird, are sensitive to the missing fundamental, a harmonic phenomenon contrary to the postulates of place theory. Starlings were trained to discriminate between a high and low tone (50 dB). After discrimination was achieved, a missing fundamental tone of the same intensity was introduced. The subjective tone was identical in pitch to the lower frequency, while the frequencies of which it was constructed surrounded the higher tone. The prediction was that if starlings heard only the component frequencies they would respond as if they had heard the higher tone. If they heard the missing fundamental they would respond as if they heard the lower tone. Results and implications will be discussed.
Sequential RT effects during recovery from an adapting stimulus
Authors: Goldman Thomas M. , Weiler Ernest M. , Kretschmer Laura , Donnelly Kenneth
Published: October 2005

Goldman, Weiler, and Davis (1981), Davis and Weiler (1975), etc. found an increase in reaction time (RT) to 400-Hz test tones accompanying a 500-Hz adapting tone. Tests were only done after 7 min of the adapting tone. Goldman et al. (1983) reported on sequential reaction times taken from 15 s to 3 min after the adapting tone began, and found that only the 15-s test showed an increase in RT, with later times not significantly different from baseline. The current data extends this finding into the “recovery” period following cessation of the 500-Hz adapting tone. The initial recovery RT showed an unexpected increase in latency followed by shorter values not significantly different from baseline. As the changes in RT during adapting did not show learning across repeated sessions, an alternate explanation based on attention will be discussed.
Measuring coherence of a surface scatter channel with a wideband parametric array
Authors: Singhal Sharad
Published: October 2005

The parametric array projects narrow beams of sound at low frequencies with small transducers. This makes it attractive for use in model tank surface scatter experiments. The sidelobe free nature of the projected beam makes it possible to describe the insonified area on the surface simply and precisely. Coherence measurements require that the parametric array transmit a known wideband signal in the water. In this paper, we describe how these signals can be synthesized adaptively using an on-line data acquisition system. The results of some measurements of the forward surface scattering coherence made at low grazing angles for various surface conditions are shown. These measurements are compared to earlier measurements made with simple projectors and to the predictions of current analytical models.
Auditory-perceptual correlates of the vowel
Authors: Miller James D.
Published: October 2005

It is hypothesized that the vowels of given language and dialect can be separately localized in the space x = log(PF3/PF2), y = log(PF1/PR), and z = log(PF2/PF1) where PF1, PF2, and PF3 are the center frequencies of the perceptual formants and PR is the value in Hz of the perceptual reference. Perceptual formants are the significant prominences in the vowel spectrum as processed by the auditory system. The perceptual reference is based on (1) the expected value of(F1/F0) for all voiced segments of all speakers, (2) the current speaker's average F0, and (3) the speaker's appropriately filtered modulations in F0. Data from many sources in the literature as well as our own measurements of vowels in syllables and sentences will be presented in support of the hypothesis that the vowel-phones of American English can be associated with nonoverlapping perceptual target zones, whether the vowels are voiced or whispered, regardless of the speaker's vocal tract characteristics, age, or sex and regardless of speech rate, phonetic context, and nasalization. As will be shown the perceptual target zones appear to have large and irregular envelopes but fit together in the manner of a three-dimensional jigsaw puzzle. [Supported by NINCDS NS03856.]
Long-wavelength acoustic propagation in ordered and disordered suapensions
Authors: Schwartz Lawrence M. , Johnson David L.
Published: October 2005

Multiple scattering theory is used to study the propagation of compressional waves in systems comprised of spherical solid grains embedded in an inviscid fluid. In the case of primitive ordered cubic suspensions the problem reduces to a system of coupled equations whose solution is shown to have the form predicted by Biot; i.e., a single geometrical parameter α, characterizes the suspension. By contrast, in disordered suspensions, we show that the Biot formula is not rigorously applicable. We argue that a proper theory must treat fluctuations in the environment of a typical grain. (This is analogous to calculating corrections to the local field in a polarizable media.) These effects introduce dependence of the long wavelength sound speed on (1) the radial (i.e., pair) distribution function and (2) higher scattering multipoles. The extent to which various approximation schemes include these fluctuations is discussed and illustrative calculations for the case of densely packed composites are presented. We point out that the available acoustic data are based on suspensions in which the fluid-solid density contrast is not great enough to distinguish between competing approximations.
Infants' recognition of cross-modal correspondences for speech: Is it based on physics or phonetics
Authors: Kuhl Patricia K. , Meltzoff Andrew N.
Published: October 2005

Four-month-old infants recognize cross-modal correspondences between the auditory and visual concomitants of speech (Kuhl and Meltzoff, 1982). In those experiments, infants were shown a filmed display of two faces, one producing the articulatory movements corresponding to /a/ and the other producing the articulatory movements corresponding to /i/. One of the sound tracks (either /a/ or /i/) was played in synchrony with the faces. Infants' visual fixations to the faces were scored. Results demonstrated that infants looked longer at the face that matched the sound being presented. Infants who heard /a/ looked longer at the /a/ face, while infants who heard /i/ looked longer at the /i/ face. We now report an experiment designed to dissociate two potential explanations for this cross-modal effect, one based on “physics,” the other on “phonetics.” We replicated the experiment, using the same visual stimuli but altered auditory stimuli. The auditory signals were pure tones that followed the first three formant frequencies of the /a/ and /i/ vowels. Results showed that listening to the nonspeech signals produced a complete reversal of the effect. When listening to the pure-tone analog of /a/, infants looked longer at /i/. When listening to the pure-tone analog of /i/, infants looked longer at /a/. [Supported by NSF and NICHD.]
Phonetic acoustic invariance and the antimetrical vocal tract shape
Authors: Ohta Kozo , Fuchi Kazuhiro
Published: October 2005

The antimetrical vocal tract shape (VTS) means the vocal tract cross-sectional area function which is estimated directly from speech waves by the PARCOR algorithm assumed that the vocal tract characteristic becomes antimetrical on utterance of vowels [K. Fuchi, Tech. Group Acoust. Soc. Jpn. Pap. S77-05 (1977)]. As the result of a detailed experiment it is shown that the essence of the phonetic quality of vowel-like sounds is fully described by the antimetrical VTS [K. Ohta and K. Fuchi, J. Acoust. Soc. Jpn. 39 (3), 173–184 (1983)]. An attempt to find a phonetic acoustic invariance is reported based on the antimetrical VTS. Articulatory quantities close to the invariance are presented in both static and dynamic cases. For the former it is demonstrated that articulatory quantities independent to interspeaker variation (between males and females, among males or among females) can be extracted by reducing a neutral VTS from shapes of five vowels for each speaker. For the latter a difference of the sound which arises in the glide of vowels is investigated. A semivowel is perceived when the vocal tract characteristic holds antimetrical during the glide, but any speech sound is not perceived when the characteristic does not hold.