bluuebunny/crossref_metadata_2025 huggingface dataset:
Relearning consonant timing: Evidence from English and Russian
Authors: Zsiga Elizabeth C.
Published: October 2005

Advocates of the gestural approach to phonetic or phonological representations argue that degree of overlap between articulatory gestures can account for many phonetic regularities (such as assimilation, deletion, or release of consonants in clusters) that can contribute to the perception of a ‘‘foreign accent’’ [C. P. Browman and L. Goldstein, Phonetica 49, 155–180 (1992); E. C. Zsiga, GURT 1995, pp. 575–587 (1995)]. The research reported here compares patterns of consonant overlap at word boundaries in English and Russian, and investigates the extent to which adult language learners transfer the timing patterns of their native language to the second language. Native Russian speakers learning English and native English speakers learning Russian produced phrases in English and Russian contrasting VC♯CV, VC♯V, and V♯CV sequences, with varying stress patterns and syntactic configurations. The ratio of closure duration in clusters as compared with single consonants [E. C. Zsiga, J. Phon. 22, 121–140 (1994)] is examined, in order to determine patterns of consonant timing in the two languages (including effects of stress and boundary strength) and to elucidate the extent to which the timing patterns of second-language speakers resemble that of native speakers.
Vowel perception in Swedish, English, and Spanish
Authors: Willerman Raquel , Kuhl Patricia K.
Published: October 2005

This study examines the role of linguistic experience in vowel perception. Two main questions are addressed: (1) How do speakers of different languages label the same area of vowel space? (2) What is the relationship between phonetic labeling and acoustic sensitivity for vowels? Identification functions and goodness ratings for the high, front quadrant of the vowel space were obtained from speakers of Swedish, English, and Spanish. Stimuli along one vector in this space were used in a discrimination task. The results show that (a) speakers of different languages label the vowels in this space in accord with their native vowel inventory, (b) rather than incorporating all areas of the vowel space into their native language categories, there is dead space where listeners say the vowels are not in their language, and (c) there are significant differences in discrimination ability between speakers of different languages which are consistent with their different identification functions. These results suggest that linguistic experience plays an important role in vowel perception.
Effects of underwater environmental conditions on vibrotactile thresholds
Authors: Verrillo Ronald T. , Bolanowski Stanley J. , Baran Frances , Smith Paul F.
Published: October 2005

The effects of low-frequency, water-borne vibration upon the cutaneous surface of swimmers and divers are virtually unknown. It has been reported that divers can ‘‘feel’’ underwater sounds on various parts of their bodies. The current experiments were conducted in two parts as initial investigations of these reports. The first experiments were to determine if changes in barometric pressure and breathing mixture have an effect on vibrotactile thresholds measured in air. Vibrotactile thresholds at the thenar eminence were measured on eight divers during two saturation dives in a dry hyperbaric chamber. Measurements were made on four subjects before and after a 6-day saturation dive that simulated an excursion to 300 feet of seawater (fsw). Measurements on another four subjects were made at 1 atmosphere absolute (ATA) before and after an 8-day simulated 300-fsw dive, and at 5, 7, and 10.1 ATA (300 fsw). The gas mixture in which the divers lived was varied according to standard procedures to prevent adverse body reactions during compression and decompression. Vibrotactile thresholds were measured by standard psychophysical methods at 1, 10, 100, and 250 Hz. Results suggest that neither increased atmospheric pressure nor breathing gas had any effect on vibrotactile thresholds within any of the four mechanoreceptor channels that innervate normal skin. The second set of experiments was performed to assess the effect of complete seawater hydration of the skin upon vibrotactile threshold sensitivity measured at the thenar eminence and the volar surface of the forearm. In-air thresholds of three subjects were measured by standard psychophysical methods at 1, 10, 100, and 250 Hz. The measurements were repeated underwater after the forearm and hand were submerged for 20 min in a seawater solution. With the exception of 1 Hz, no statistically significant changes were found at either site when compared to threshold measured in air. At 1 Hz there appears to be an increase in sensitivity of approximately 3 dB when the skin is hydrated with seawater.
Comments on ‘‘Comparisons of vibration frequencies for rods and beams from one-dimensional and three-dimensional analyses’’ [J. Acoust. Soc. Am. 98, 2122–2135 (1995)]
Authors: Hutchinson James R.
Published: October 2005

Leissa and So use accurate solutions generated by the Rayleigh–Ritz procedure as a basis of comparison for the one-dimensional theories for longitudinal, torsional, and bending vibrations of rods and beams. They considered both the free–free and fixed–free cases. In the past I have considered similar comparisons, for the free–free case, based on a series solution. A comparison of my series solution with the authors Rayleigh–Ritz solution showed some disagreements. Those disagreements are tabulated. The authors did not use the best shear coefficient in their comparison, nor did they compare the Pickett solution which they reference. Comparisons using Timoshenko’s shear coefficient and Pickett’s solution are also presented in this comment.
Comments on ‘‘Accurate vibration frequencies of circular cylinders from three-dimensional analysis’’ [J. Acoust. Soc. Am. 98, 2136–2141 (1995)]
Authors: Hutchinson James R.
Published: October 2005

Leissa and So presented accurate frequencies for solid cylinders using the Rayleigh–Ritz method for both a completely traction-free solid cylinder and a solid cylinder which is fixed at one end. They compared their frequencies for the traction-free case with my series solution in their Tables VI and VII. The comparison does not demonstrate the accuracy which can be achieved with the series solution. A table demonstrating the convergence of the series solution is presented in this Comment. Discrepancies were found between the Rayleigh–Ritz solutions and the converged series solution for some of the frequencies in Table VI. Further discrepancies were found in some of the other results. All discrepancies are tabulated for the traction-free case.
Response to ‘‘Comments on ‘Accurate vibration frequencies of circular cylinders from three-dimensional analysis’ ’’ [J. Acoust. Soc. Am. 100, 1894–1895 (1996)]
Authors: Leissa Arthur , So Jinyoung
Published: October 2005

The authors respond to the comments by Hutchinson.
Distortion product otoacoustic emissions created through the interaction of spontaneous otoacoustic emissions and externally generated tones
Authors: Norrix Linda W. , Glattke Theodore J.
Published: October 2005

Spontaneous otoacoustic emissions (SOAEs) and external tones (XTs) were used as primaries f2 and f1, respectively (frequency of f2≳f1) to create 2f1−f2 distortion product otoacoustic emissions (DPOAEs). Amplitude and frequency of the SOAEs, XTs, and DPOAEs were recorded by placing a sensitive microphone in the ear canal and extracted using fast Fourier transform analysis. XTs were presented to ten ears at SOAE/f1 ratios between 1.08 and 1.22. XTs were incremented in 5-dB steps and ranged from levels equal to the initial SOAE amplitudes to levels at which the SOAEs and DPOAEs were suppressed into the noise floor. Results indicated that DPOAE amplitudes and SOAE suppression characteristics were idiosyncratic. Despite the variability, the following trends were noted: (1) at larger frequency ratios, DPOAE generation and SOAE suppression were associated with greater XT levels; (2) DPOAE growth functions were characterized by slopes less than 1 dB/dB, a maximum, rollover and disappearance into the noise floor with increasing XT levels; (3) maximum amplitude DPOAEs were observed at frequencies approximately one-half octave lower than the SOAE (f2); (4) the presence of DPOAEs was associated with SOAE suppression; (5) the most common SOAE frequency shift, in the presence of XT stimulation, was a shift to a higher frequency.
The use of cumulative distributions to determine critical values and levels of confidence for clinical distortion product otoacoustic emission measurements
Authors: Gorga Michael P. , Stover Lisa , Neely Stephen T. , Montoya Danielle
Published: October 2005

Distortion product otoacoustic emission (DPOAE) input/output functions were measured at nine f2 frequencies ranging from 500 to 8000 Hz in 210 normal-hearing and hearing-impaired subjects. In a companion paper [Stover et al., J. Acoust. Soc. Am. 100, 956–967 (1996)], L1−L2 was held constant at 10 dB, and L2 was varied from 65 to 10 dB SPL in 5-dB steps. Based upon analyses using clinical decision theory, it was demonstrated that DPOAE amplitudes for 65/55 dB SPL primaries (L1/L2) and DPOAE thresholds resulted in the greatest separation between normal and impaired ears. In this paper, the data for these two conditions were recast as cumulative distributions, which not only describe the extent of overlap between normal and impaired distributions, but also provide the measured value (i.e., the specific DPOAE amplitude or threshold) for any combination of hit and false alarm rates. From these distributions, confidence limits were constructed for both DPOAE amplitude and threshold to determine the degree of certainty with which any measured response could be assigned to either the normal or impaired population. For these analyses, DPOAE measurements were divided into three categories (a) response properties that would be unlikely to come from normal ears, (b) response properties that would be unlikely to come from impaired ears, and (c) response properties for which hearing status was uncertain. Based upon DPOAE amplitude measurements, the region of uncertainty, defined between the 95 percentile for impaired ears and the 5 percentile for normal ears, was relatively narrow for f2 frequencies ranging from 707 to 4000 Hz. For DPOAE thresholds, this region was relatively narrow for f2 frequencies ranging from 1414 to 4000 Hz.
Effects of stimulus rate on the feline brain-stem auditory evoked response during development. II. Peak amplitudes
Authors: Burkard Robert , McGee JoAnn , Walsh Edward J.
Published: October 2005

The effects of click rate on brain-stem auditory evoked response (BAER) peak amplitudes were investigated in adult cats and kittens in four age groups: 10, 15, 20, and 30 post-natal days. Conventional BAERs were obtained at rates of 5, 10, 30, 60, and 90 Hz. Maximum length sequences (MLSs) were used to obtain responses at rates of 83, 125, 250, 500, and 1000 Hz. For both techniques, clicks were presented at 90 dB pSPL, and at 20 dB above threshold (20 dB SL). BAERs were observed for all age groups, at all click rates. However, not all peaks could be identified in all animals, with peak absence more common for the youngest kittens at the higher rates. BAER waves i through iv decreased in amplitude with increasing click rate for all age groups. In general, the smallest peak amplitudes were observed for the youngest animals (10- to 15-day-old) studied, while the largest amplitudes were found for the adult, 20- or 30-day-old animals, regardless of rate. When amplitudes were normalized to eliminate the influences of differences in absolute values due to developmental stage (i.e., made proportional to the amplitude observed at 5 Hz), the younger age groups exhibited enhanced sensitivity to the effects of stimulus rate. However, exceptions to this trend were observed. In general, amplitudes of BAER peaks obtained with the MLS procedure were smaller than those obtained using conventional averaging with a similar average click rate, regardless of age. Finally, the most efficient method for obtaining a response at a criterion signal-to-noise ratio was typically by the use of conventional averaging at a rate of 60 or 90 Hz, for all peaks and age groups. Overall, these data suggest that higher stimulus rates produce greater neural adaptation resulting in reduced BAER peak amplitudes. The mechanism responsible for the acquisition of adult-like adaptation properties appears to develop during the early post-natal period in the cat.
Three-dimensional waves in layered media with nonparallel and curved interfaces: A theoretical approach
Authors: Kühnicke Elfgard
Published: October 2005

A calculation method is presented for transducer-generated three-dimensional, transient wave fields in layered media with curved interfaces by using a separation approach in combination with integral transform methods and point source synthesis. The transducer-specimen module is decomposed into different layers and the wave propagation is calculated separately in each layer. To simplify the boundary conditions, the existence of a thin liquid layer between two solid media is used. Using generalized ray theory it can be shown that the normal stress on the interface caused by an incident wave provides sufficient information to calculate the transmitted waves in the adjacent media. Two different functions for the point sources of the exciting element and the source function for normal stress are derived. By means of a source function for normal stress, the transmitted transient wave can be determined from the normal-stress distribution on the interface. The method is demonstrated by two examples.
On transversal structure of finite amplitude Lamb waves in the atmosphere near the Earth’s surface
Authors: Khmelevskaja-Plotnikova G. , Pavlov V.
Published: October 2005

A nonlinear evolution equation for propagation of surface waves in the Earth’s atmosphere (named Lamb waves) is deduced. This equation allows the study of the transversal structure of harmonic or aleatory waves on the boundary (boundary condition). The transversal distribution of higher harmonics of these waves is studied.
Acoustic radiation pressure in a three-dimensional lossy medium
Authors: Jiang Zhong-Yue , Greenleaf James F.
Published: October 2005

Acoustic radiation pressure exerted by an arbitrary acoustic wave in a three-dimensional lossy medium is calculated by extending an indirect approach developed by Chu and Apfel [B-T. Chu and R. E. Apfel, ‘‘Acoustic radiation pressure produced by a beam of sound,’’ J. Acoust. Soc. Am. 72, 1673–1687 (1982)]. Without appealing to the detailed solutions of equations governing fluid motion, a general analytic expression for the radiation pressure in lossy media with arbitrary waves is obtained. When an infinite lossy medium is considered, the expression states that the radiation pressure, to the lowest order of approximation (i.e., second order), is equal to corresponding total energy density. For a special class of confined spaces, the expression leads to a rather general formula for the radiation pressure, in which the radiation pressure is given in terms of various energy densities in the field. Furthermore, a relationship among these energy densities is generalized to the case of lossy media, which enables one to compute the radiation pressure in the class of spaces with the knowledge of the first-order perturbation solution only.
On the spatial coherence and angular spreading of sound forward scattered from the sea surface: Measurements and interpretive model
Authors: Dahl Peter H.
Published: October 2005

Measurements of the spatial coherence of high-frequency sound forward scattered from the sea surface are discussed, along with a simple interpretive model. The data originate from an experiment off the southern California coast using the research platform FLIP. Measurements were made using omnidirectional sources suspended from a spar buoy (tethered to FLIP) and a line array mounted on FLIP’s hull; the range varied between 500 and 1000 m. The combination of high frequency and large surface roughness makes the roughness parameter χ ≫1. The spatial coherence was measured across a line array oriented transverse to the direction of propagation, thereby giving an estimate of the horizontal coherence. The data are interpreted with a model based on the geometrical-optics limit of the Kirchhoff approximation, and a bubble scattering mechanism is also discussed. A concise expression is derived for the rms horizontal angular width σθh in surface forward scattering.
Role of the admittance operator in rough-surface scattering
Authors: Milder D. Michael
Published: October 2005

The linear operator that relates the normal gradient of a wave field to its values on an irregular surface is the basis for a new formulation of the rough-surface scattering problem. This formulation has led to a class of approximations that surpass traditional methods in accuracy and efficiency. The connection between this approach and the standard formulation by means of a boundary integral equation is the subject of this paper. While equivalent in all respects, the admittance operator formulation provides helpful new perspectives on the physics of surface scattering and lends itself naturally to more elaborate problems. For example at a rough boundary between dissimilar media, the operators compose themselves into generalized reflection and transmission operators; while at a random surface the operator terms lead to analytic forms for the scattered field moments.
Effective ultrasonic transmission coefficient for randomly rough surfaces
Authors: Hollman Kyle W. , Holland Mark R. , Miller James G. , Nagy Peter B. , Rose James H.
Published: October 2005

Rough surfaces can introduce large losses in the measured signal of transmitted ultrasonic beams detected with phase-sensitive transducers. It is shown that the ensemble-averaged transmitted wave can be exactly described by a frequency-dependent transmission coefficient for a plane wave normally incident on a single, planar, fluid–solid interface with spatially uniform, random roughness. One consequence of this is that the roughness-induced, spatially averaged signal loss is largely independent of the experimental setup; such as, for example, the transducer’s size or shape, its distance from the rough interface or for weak focusing, the focal length. We demonstrate this independence from experimental setup by presenting measurements (for near-normal incidence in a water-immersion experiment) of the roughness-induced frequency-dependent (2–8 MHz) transmission loss of the spatially averaged signal for focused, planar and array probes at a variety of distances from a specially prepared plate that had been roughened on one side. The experimentally measured single-transmission loss was found to be nearly independent of the transducer parameters described above and, for the sample studied, to be well predicted by the phase-screen approximation to the rough-surface transmission coefficient, TR≊exp(−Δk2h2/2), where Δk is the change in wave number at the fluid–solid interface and h≊54 μm is the root-mean-squared (rms) height of the surface.
In-plane and out-of-plane waves’ power transmission through an L-plate junction using the mobility power flow approach
Authors: Cuschieri J. M. , McCollum M. D.
Published: October 2005

The structural power flow through the junction between two flat plates, coupled in an L-shaped configuration, is considered using the mobility power flow (MPF) approach, for both in-plane (longitudinal and shear) and out-of-plane (bending) waves’ propagation. Power flow by both types of waves is included by considering the junction edge between the two plates, when uncoupled, to be free. Mobility expressions are then derived for both in-plane and out-of-plane degrees of freedom forces and responses. The results of the analysis show that the in-plane waves do not significantly contribute to the structural power flow at relatively low frequencies, that is, for frequencies below a bending wave number and plate thickness product of approximately 0.1. In this case, the power flow results are not different from those obtained if the junction is assumed to be pinned, and power is transmitted by only the out-of-plane waves. However, as the frequency increases, the significance of the in-plane waves’ contribution increases, and for a bending wave number and plate thickness product greater than approximately 1.0, the contribution from the in-plane waves dominates. This condition is different from the well-known result that if the thickness is greater than approximately 10% of the bending wavelength, simple bending theory does not apply. This condition deals with the significance of the in-plane waves. In the frequency region where the in-plane waves dominate, the in-plane longitudinal waves are more significant than the in-plane shear waves, although this has some dependence on the selected L-shaped configuration. The in-plane longitudinal waves couple directly to the out-of-plane waves because of the 90 degree junction.
A generalized approximation for the Cramer–Rao lower bound on direction-of-arrival estimates for a pair of closely spaced sources
Authors: Swingler D. N. , Gregory S.
Published: October 2005

It is demonstrated that the Cramer–Rao lower bound on direction-of-arrival estimation with two closely spaced, narrow-band plane waves, with an arbitrary correlation coefficient, impinging on a uniform line array, is well-approximated by an empirically derived, nonmatrix expression combining two previously published, special-case approximations. The approximation is useful for a number of sensors down to about 6, signal-to-noise ratios from about −30 to +30 dB, and source separations down to about one-sixth of a Rayleigh beamwidth. The root mean square error is about 11%.
The cubic distortion product otoacoustic emissions from the normal and noise-damaged chinchilla cochlea
Authors: Hamernik Roger P. , Ahroon William A. , Lei Sheau-Fang
Published: October 2005

A normative study of the cubic distortion product emissions from 104 monaural and binaural chinchillas was undertaken to establish criteria upon which noise exposed animals could be evaluated. From this normative group, 47 randomly selected chinchillas were exposed to various high level (150-, 155-, and 160-dB peak SPL) impulse noises. Auditory evoked potentials and cubic distortion product otoacoustic emissions were measured on each animal pre- and post-exposure and related to the sensory cell populations 30 days post-exposure. Both group mean and individual animal data indicated that the distortion product emissions were more sensitive, frequency-specific indices of noise-induced cochlear effects than pure-tone threshold measures. This was particularly evident near the threshold for noise-induced damage to the outer hair cell system.
Loudness enhancement and intensity discrimination under forward and backward masking
Authors: Plack Christopher J.
Published: October 2005

There is a large deterioration in intensity discrimination performance at medium levels for a 30-ms sinusoidal pedestal presented 100 ms before or 100 ms after an intense masker [Plack and Viemeister, J. Acoust. Soc. Am. 92, 3097–3101 (1992)]. It has also been demonstrated that the loudness of a 30-ms sinusoidal tone burst, presented 100 ms after a masking tone burst, is enhanced at mid-levels [Zeng, J. Acoust. Soc. Am. 96, 2127–2131 (1994)]. The present experiment measured intensity discrimination and loudness enhancement in both forward and backward masking. A double-staircase adaptive procedure was used to match the loudness of a 30-ms, 1-kHz standard sinusoid presented in quiet to the loudness of a 30-ms, 1-kHz sinusoid presented 100 ms after (forward masking) or 100 ms before (backward masking) a 110-ms, 90-dB, 1-kHz masking sinusoid. The mean of the thresholds from the two staircases was used to determine the amount of enhancement, and the difference between the thresholds from the two staircases was used to determine the intensity just noticeable difference (jnd). Four listeners were tested at a range of standard levels between 30 and 90 dB. For all listeners, in both forward and backward masking, the jnd and loudness were greatest at mid-levels (40–70 dB). For a given listener, there was no substantial difference between the form of the results under forward compared to backward masking, although there was considerable variability in the size of the effects between the individual listeners. Combining all the data, for both forward and backward masking there was a positive correlation between the size of the jnd and the magnitude of the loudness enhancement, although the correlation was only significant in backward masking (p<0.005). Taken with the results of Zeng, these data suggest a link between loudness enhancement and the jnd increase, and a link between the mechanisms underlying the effects of forward and backward masking on intensity discrimination. It is suggested that all these effects may be caused by long-term loudness integration in the auditory system.
Temporal factors in referential intensity coding
Authors: Plack Christopher J.
Published: October 2005

Three experiments investigated the finding [Plack et al., J. Acoust. Soc. Am. 97, 1141–1149 (1995)] that intensity discrimination under backward masking can be improved by presenting an additional, ‘‘proximal,’’ tone burst shortly before or after the pedestal. All the stimuli used in the experiments were 30-ms, 1-kHz sinusoids. In the first experiment, intensity discrimination was measured for a 50-dB SPL pedestal presented 100 ms before an 80 dB SPL masker. A proximal tone burst was presented either before or after the pedestal, separated from the pedestal by a brief silent gap. For the conditions in which the proximal burst was before the pedestal, adding a proximal burst with a higher level than the pedestal produced an improvement in intensity discrimination. The most effective level of the proximal burst increased as the gap was increased. For the conditions in which the proximal burst was after the pedestal, two listeners showed an improvement when the proximal burst was lower in level than the pedestal, and one listener showed an improvement when the proximal burst was higher in level than the pedestal. In a second experiment, detection threshold measurements showed that good performance was not dependent on the proximal burst masking the pedestal in one of the two observation intervals. The final experiment used a selective training procedure to demonstrate that listeners were basing performance on two conflicting strategies, namely, to pick the interval that sounded as if it had three tone bursts in it when the proximal level was higher than the pedestal level, and to pick the interval that sounded as if it had two tone bursts in it when the proximal level was lower than the pedestal level. A model of temporal resolution is presented that can explain certain aspects of the results in terms of the detection of ‘‘bumps’’ in the temporal excitation patterns produced by the stimuli. In conditions of backward masking, these relative features seem to provide a superior cue for intensity discrimination than absolute intensity, which is actively rejected as a cue.
Vowel discrimination in cats: Thresholds for the detection of second formant changes in the vowel /ε/
Authors: Hienz Robert D. , Aleszczyk Cynthia M. , May Bradford J.
Published: October 2005

The ability of cats to discriminate changes in the second formant of the vowel /ε/ was examined across a range of stimulus levels. Cats were trained to press and hold down a lever to produce a pulsed train of the standard vowel /ε/, and to release the lever only when a variant of /ε/ occurred. Six synthetic variants of /ε/ had the same first and third formants (F1 and F3), but with the second formant (F2) located between 1700 and 2000 Hz. All stimuli were tested at levels of 10, 30, 50, and 70 dB SPL. Average difference thresholds for changes in F2(ΔF2) of the vowel /ε/ ranged from 87 to 36 Hz across levels of 10 to 70 dB SPL, and were only slightly above those of humans. Further, the ΔF2 values were lower than pure-tone ΔF values in the same frequency range, whereas humans exhibit higher ΔF2 values than pure-tone ΔF values in the same frequency range. Changes in the second formant in a negative direction (downward F2 shifts) were also found to be more difficult to detect than upward F2 shifts. These results suggest that, compared to pure tones, cats are better able to discriminate small changes in more complex, vowel-like stimuli.
Sound orientation behavior in cats. I. Localization of broadband noise
Authors: May Bradford J. , Huang Aileen Y.
Published: October 2005

Behavioral experiments measured the accuracy of the cat’s voluntary head orientation responses to bursts of broadband noise at 104 locations in the frontal sound field. Cats were presented sound stimuli at randomly selected locations and received a food reward for releasing a lever when a light-emitting diode (LED) flashed at the same location. Head movements to the perceived location of the acoustic stimulus, and therefore expected location of the LED cue, were tracked by an electromagnetic sensor. Orientation responses to single sound bursts were directed to within 5° of the azimuth and elevation of sounds within 15° of the immediate frontal field and did not change for burst durations of 40, 100, and 200 ms. An increasing underestimation of target location was observed as the sound stimulus moved to more lateral azimuths and higher elevations. The ‘‘undershoot’’ phenomenon was reduced by allowing subjects to track paired stimulus bursts that repeated from the same location. These effects of sound location on the accuracy of orientation responses are predicted by the availability of mid-frequency spectral cues for sound localization.
Sound orientation behavior in cats. II. Mid-frequency spectral cues for sound localization
Authors: Huang Aileen Y. , May Bradford J.
Published: October 2005

The cat’s head-related transfer function creates a directionally dependent mid-frequency notch in the amplitude spectrum of a broadband sound as the stimulus propagates to the tympanic membrane [Rice et al., Hear. Res. 58, 132–152 (1992)]. Our previous behavioral studies [May and Huang, J. Acoust. Soc. Am. 100, 1059–1069 (1996)] have indicated that the cat’s sound-evoked orientation responses are well directed to the azimuth and elevation of broadband noise bursts in the frontal sound field, where pinna-based spectral notches are prominent and change systematically with sound direction. In the present study, the importance of mid-frequency directional cues in the cat’s sound localization behavior was further evaluated by manipulating the frequency and bandwidth of orientation stimuli. The accurate pattern of orientation behavior seen previously with bursts of broadband noise was relatively unaffected when stimulus bandwidth was decreased to mid-frequency bandpass noise of 5–18 kHz. In contrast, poorly directed head orientation responses were observed in tests with high-pass noise (≳18 kHz) and mid-frequency pure tones. When tested with narrow bands of mid-frequency noise, cats oriented toward the spatial location where HRTF-filtering properties most closely matched the stimulus spectrum. These results suggest that important sound localization cues are derived from mid-frequency spectral features of the cat’s HRTF.
The perception of temporal patterns for electrical stimulation presented at one or two intracochlear sites
Authors: McKay Colette M. , McDermott Hugh J.
Published: October 2005

The question of how well the temporal structure in pulsatile electrical stimulation is perceived, and the nature of the information that may be conveyed by this temporal structure, is of importance to the further development of speech processing strategies for cochlear implants. The two experiments described here investigated the perception of temporal fine structure in amplitude modulated 1-kHz pulse trains, both when a single electrode position was used, and when the pulses alternated between two electrode positions. Five subjects with the Mini System 22 implant took part in these experiments. The amplitude modulations were constructed so that all dual-electrode stimuli had the same temporal pattern on each individual electrode but differed in the aggregate temporal pattern. A hypothesis was investigated that subjects perceive the aggregate temporal pattern rather than the pattern at each individual electrode place, only when the electrodes are less than a critical distance apart. The first of these two experiments used a four-interval forced-choice task to measure the ability of subjects to detect changes in the aggregate temporal pattern. At electrode distances greater than 3 to 4 mm, subjects could no longer perceive the aggregate pattern, confirming the hypothesis. The second experiment used a single-interval pitch estimation task to test the hypothesis that the perceptual differences in temporal patterns measured in the previous experiment were classified similarly to rate pitch differences by the subjects. The results confirmed this hypothesis, and showed that the pitch of the modulated stimuli could be predicted by the expected inter-pulse intervals in the excited neural population.
A comparison of speech envelopes of stutterers and nonstutterers
Authors: Kuniszyk-Jóźkowiak Wiesl/awa
Published: October 2005

A new parameter, the area under the speech envelope, was used to evaluate the degree of speech dysfluency in stutterers. This parameter has been measured for 100-s utterances of 30 fluent speakers and 30 stutterers speaking with simultaneous auditory feedback (SAF) and delayed auditory feedback (DAF). A correlation was found between the area under the speech envelope and the severity of stuttering. Thus for stutterers, this parameter can be used to evaluate the degree of the disturbance of fluency. The values of this parameter were significantly higher in fluent utterances than in nonfluent ones. The reduction of stuttering observed in stutterers under DAF was accompanied by an increase of the area under the speech envelope, making it comparable to the one measured for the utterances of fluent speakers.
Speech versus nonspeech in pitch memory
Authors: Semal Catherine , Demany Laurent , Ueda Kazuo , Hallé Pierre-André
Published: October 2005

The memory trace of the pitch sensation induced by a standard tone (S) can be strongly degraded by subsequently intervening sounds (I). Deutsch [Science 168, 1604–1605 (1970)] suggested that the degradation is much weaker when the I sounds are words than when they are tones. In Deutsch’s study, however, the pitch relations between S and the I words were not controlled. The first experiment reported here was similar to that of Deutsch except that the speech and nonspeech stimuli used as I sounds were matched in pitch. The speech stimuli were monosyllabic words derived from recordings of a real voice, whereas the nonspeech stimuli were harmonic complex tones with a flat spectral profile. These two kinds of I sounds were presented at a variable pitch distance (Δ-pitch) from the S tone. In a same/different paradigm, S had to be compared with a tone presented 6 s later; this comparison tone could be either identical to S or shifted in pitch by ±75 cents. The nature of the I sounds (spoken words versus tones) affected discrimination performance, but markedly less than did Δ-pitch. Performance was better when Δ-pitch was large than when it was small, for the speech as well as nonspeech I sounds. In a second experiment, the S sounds and comparison sounds were spoken words instead of tones. The differences to be detected were restricted to shifts in fundamental frequency (and thus pitch), the other acoustic attributes of the words being left unchanged. Again, discrimination performance was positively related to Δ-pitch. This time, the nature of the I sounds (words versus tones) had no significant effect. Overall, the results suggest that, in auditory short-term memory, the pitch of speech sounds is not stored differently from the pitch of nonspeech sounds.
Modeling the perception of concurrent vowels: Role of formant transitions
Authors: Assmann Peter F.
Published: October 2005

When two synthetic vowels are presented concurrently and monaurally, listeners identify the members of the pair more accurately if they differ in fundamental frequency (F0), or if one of them is preceded or followed by formant transitions that specify a glide or liquid consonant. However, formant transitions do not help listeners identify the vowel to which they are linked; instead, they make the competing vowel easier to identify. One explanation is that the formant transition region provides a brief time interval during which the competing vowel is perceptually more prominent. This interpretation is supported by the predictions of two computational models of the identification of concurrent vowels that (i) perform a frequency analysis using a bank of bandpass filters, (ii) analyze the waveform in each channel using a brief, sliding temporal window, and (iii) determine which region of the signal provides the strongest evidence of each vowel. Model A [Culling and Darwin, J. Acoust. Soc. Am. 95, 1559–1569 (1994)] computes the rms energy in each channel at successive time intervals to generate running excitation patterns that serve as input to a vowel classifier, implemented as a linear associative neural network. Model B uses a temporal analysis in each channel to generate running autocorrelation functions, and it includes a further stage of source segregation [Meddis and Hewitt, J. Acoust. Soc. Am. 91, 233–245 (1992)] to partition the channels into two groups, one group containing evidence of the periodicity of the vowel with the dominant F0, the other group providing evidence of the competing vowel. Both models predicted effects of F0 and formant transitions on identification, but model B provided more accurate predictions of the pattern of listeners’ identification responses. Taken together, the empirical and modeling results support the idea that the identification of concurrent vowels involves an analysis of the composite waveform using a sliding temporal window, combined with a form of F0-guided source segregation.
Evaluation of the acoustical stiffness of saxophone reeds under playing conditions by using the reactive power approach
Authors: Boutillon Xavier , Gibiat Vincent
Published: October 2005

The dynamics of a saxophone reed has been analyzed by means of the simplest model—one pure spring—acceptable for frequencies below the resonance frequency of the reed. As proposed in the context of bowed string dynamics [J. Acoust. Soc. Am. 90, 754–763 (1991)], a reactive power is defined for the air-column of a saxophone and its reed. When the instrument sustains a harmonic tone, a balance between those two reactive powers can be established, as a generalization onto a multimodal system of the usual condition sin(φ)=0 that a simple oscillator fulfills when it vibrates at its resonance frequency. The stiffness of the reed can be derived from that condition. Experiments were carried out on a saxophone played by a professional musician. The reed stiffness under playing conditions is determined after separate measurements of the input impedance (TMTC method) and of the internal pressure spectrum. Results are comparable with compliance values measured on isolated reeds by other authors.
Elastic wave power equipartition in a finite-length ringed shell
Authors: He Hua , Dyer Ira
Published: October 2005

Compressional and shear waves, trace matched on a submerged cylindrical shell by plane sound incidence near beam aspect, can couple to each other, as well as to subsonic flexural waves, at ring stiffeners and endcaps. This paper addresses whether the power in each elastic wave type (defined as energy per unit shell length multiplied by the wave axial group speed) is partitioned equally with the other two. Shell surface velocities of a ringed shell, calculated for midfrequency range 2<ka<12 via a SARA 2-D program implemented by Liu, are Fourier transformed into the wave-number domain to evaluate each wave type, and then into the time domain to evaluate transient wave power in several time windows. The time windows are based on an integral number of roundtrips of the trace matched wave in the shell. It is found that elastic wave power among the wave types differs by 10 dB in the first window, and therefore is not equipartitioned. However, the wave power difference is within 3 dB in the second window, which supports the conclusion of at least approximate wave power equipartition. [Research supported by ONR.]
Topology optimization analysis for reduction of interior noise using a homogenization method for a mean eigenvalue
Authors: Kozukue Wakae , Hagiwara Ichiro
Published: October 2005

Shape and topology optimization analysis using a homogenization method has received much attention because it can treat topological changes of a design domain. However, as far as dynamic problems are concerned, it has not been successfully applied until recently. Here, it is applied to the reduction of interior noise in the coupled structural–acoustic system for the first time. Attempts were made to reduce the mean eigenvalue formulated by Ma et al. and the sound-pressure level integral formulated by Kozukue et al. by using a homogenization method, and the validity of these combined methods is demonstrated.
Measurement of the parameters needed for energy finite-element analysis of sound and vibration
Authors: Unglenieks Robert J. , Bernhard Robert J.
Published: October 2005

Energy finite-element models of structural acoustic systems require input of transmission and reflection coefficients at the joints between systems as well as loss factors and group speeds of the media. Methods have been reported previously for measurement of these properties [R. J. Unglenieks and R. J. Bernhard, J. Acoust. Soc. Am. 97, 3331(A) (1995)]. In this paper, measured parameters for the round robin T-beam structure and a bolted joint will be shown. The results for the T-beam compare well with theoretical values for thick beam behavior. The bolted beam study was used to examine the variation that might be encountered in assembled systems. The variation was found to be significant. Energy finite-element predictions of the response compared favorably to measured results.
An energy method for midfrequency and low modal overlap
Authors: Bremner Paul , Langley Robin
Published: October 2005

Some new work has been done on the use of discrete modes to improve the spatial and spectral variance of statistical energy analysis (SEA) estimates of structure-borne noise at ‘‘midfrequencies.’’ For any given frequency band one can partition the subsystem into two groups—high and low modal overlap. Phase-correlated responses across junctions of low modal overlap subsystems (e.g., beams) suggest that at low to midfrequencies, their response is better described by a ‘‘global’’ mode set. These modes are generally few in number and can be estimated with numerical eigensolvers by assuming that the separate set of high modal overlap subsystems contributes only nonresonant stiffness or mass. Coupling loss factors between high and low modal overlap subsystems defined in this new way can be estimated using a generalized Green’s-function form [R. S. Langley, J. Sound Vib. 141, 207–219 (1990)]. Results are presented for the sharing of energy between a low and high modal overlap beam network, with comparison to an ‘‘exact’’ dynamic stiffness solution and SEA. There is a very satisfactory improvement in spectral variance at midfrequencies. [Work supported by RESOUND Consortium.]
Prediction of sound inside an automobile due to wind noise
Authors: Strumolo Gary S.
Published: October 2005

A mathematical model and computer program has been developed to predict the sound inside an automotive passenger compartment due to wind noise. Using steady-state information on pressure distributions along the glass surfaces, the program computes the impact of vortices on the vibrational characteristics of the glass and the radiated sound from it. It also accounts for the sound radiated through the door seals and combines them for a composite sound-pressure level (SPL) estimate at the driver’s ear location. This SPL spectrum is computed at the 1/3-oct frequencies from 25 Hz to 10 kHz. The program also computes the overall SPL, loudness, and % speech intelligibility. Using optimization techniques, the model allows for a desired SPL spectrum to be specified along with a set of design variables. It then automatically computes the values needed by these variables to come as close as possible to the desired spectrum. The model has been validated over a wide range of cars and trucks. Typical accuracy is ± 3 dB within the frequency range, ± 1 dB for the overall SPL. Examples will be shown demonstrating this accuracy and illustrating how this system can help design quieter road vehicles.
An innovative noise and vibration suppression technique based on the combination of vibration control by confinement and layered damping approaches
Authors: Tarnowski David , Allaei Daryoush , Landin Donald , Chen Chi-Ping , Liu Shaobo
Published: October 2005

A feasibility study was conducted to demonstrate that vibration control by confinement (VCC) is a viable approach to today’s noise and vibration problems. Two types of structures were examined. First, a finite beam carrying a critical component on one side and subjected to harmonic disturbances on the other side was simulated. In this part of the investigation, the vibration suppression criterion was to minimize vibrations transmitted to the critical component. The VCC approach was compared with current passive methods, such as tuned isolators, vibration absorbers, and two cases of layered damping. As the second example, a plate, resembling the panel section of a car door, was investigated. The plate was subjected to transient and harmonic excitations. The objective was to determine the degree of improvement on the effectiveness of layered damping materials when used in conjunction with VCC. The results of the computer simulation combining VCC with layered damping materials covering 100% and 63% of the plate were of interest in this study. The finite element method was used to model both structures. Results clearly show that VCC can be used as a stand-alone mechanism to suppress or isolate vibrations, or combined with layered damping materials to significantly improve performance. [Work supported jointly by QRDC, Inc., 3M, and the Department of Defense.]
Intelligibility of speech with filtered time trajectories of LPC cepstrum
Authors: Arai Takayuki , Pavel Misha , Hermansky Hynek , Avendano Carlos
Published: October 2005

One of the main objectives of front-end processing in robust automatic speech recognition (ASR) is to preserve critical linguistic information while suppressing irrelevant information such as speaker-specific characteristics, channel characteristics, and noise. Since the information suppressed in the front end of the recognizer is lost for the recognition process, it is important to identify those features of the signal that are critical for human speech communication. This work examines effects of temporal filtering of the time trajectories of LPC cepstrum. Results of the perceptual experiments show that intelligibility of Japanese syllables is not severely impaired as long as remaining spectral envelope components have a rate of change between about 1 and 20 Hz. Analysis of results for each phoneme class is also reported. [Work supported by DoD under MDA-904-94-C-6169.]