摘要:

Perfusion of the choclea with artificial perilymph containing high concentrations of potassium chloride selectively induces the release of several different endogenous amino acids [Neurosci. Abstr.16.1(1983)]. This study examines whether such augmentations reflect the liberation of neurotransmitter(s) from depolarized hair cells by comparing potassium‐induced changes in amino acid levels evoked under normal divalent ion conditions(2.0 mM Ca+2−1.0 mM Mg+2)to the effects of potassium elicited under conditions known to antagonize evoked transmitter release(0.1 mM Ca+2−20.0 mM Mg+2). For each condition, high performance liquid chromatographic analyses were conducted on artificial perilymph samples collected before, during, and after the perfusion (scala tympani →scala vestibuli) of 50‐mM potassium perilymph. Analysis of variance and subsequent Newman‐Keuls multiple range tests were conducted on mean sample concentration values (N= 5/condition) for each of 17 endogenous amino acids. Exposure to0.1 mM Ca+2−20 mM Mg+2resulted in attenuations of evoked release only for amines identified as glutamate (− 39.6%,p= 0.005) and taurine ( − 48.2%,p= 0.003). These data support the candidacy of glutamate and taurine as auditory receptoneuronal neurotransmitters or transmitter metabolites. [Supported by NIH Grants NS‐06575, NS‐16080, NS‐07058, and NSF Grant BNS‐8118772.]

ISSN:0001-4966    

DOI:10.1121/1.2021639

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Spectra of running speech of eight female subjects were determined for two conditions: loud reading and reading of the same text in whispered mode. The subjects were seated in a sound isolated booth. A12‐in.measuring microphone was 10 cm from the lips of the reader. The spectrum analyzer Nicolet UA 500 A was employed. The average spectrum of the eight subjects had a pronounced maximum at 300 Hz when the speech was loud. Between 500 and 1200 Hz the slope was around −17 dB/oct, and between 1.8 and 14 kHz the slope was −3.7 dB/oct. The whispered speech had very similar spectrum in the upper frequency range mentioned above. The spectrum had the same average slope. Below 1000 Hz the average whispered speech spectrum was rather flat. The differences between whispered and loud spectral levels in this range reached around 20‐dB values.

ISSN:0001-4966    

DOI:10.1121/1.2021643

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

An understanding of natural language durations will lead to more intelligible synthetic speech, and to improved automatic recognition. Toward this goal, a I I I‐word paragraph was read by 29 native French speakers. A pitch‐extractor device plotted the speech amplitude waveform, at an average rate of 55 mm/s. Durations were measured to the nearest 5 ms, with a measurement error of about 10 ms (1/2 mm). Phoneme durations were found to be significantly shorter than those in stressed words from sentences pronounced in isolation [D. O'Shanghnessy, J. Phon.9, 385–406 (1981)]. Previous trends (short schwa vowels and grammatical words, long unvoiced fricatives, nasal vowels, and prepausal syllables) were confirmed. Vowels lengthened preceding voiced fricatives (but not prior to /r/, and lengthened more at sentence‐internal pauses than at the end of a sentence. Standard deviations of phoneme durations (at a fixed position in the paragraph) across speakers averaged about 20% for consonants and 25% for vowels. A generative model of French durations will be presented. [Supported by NSERC and the France‐Quebec exchange.]

ISSN:0001-4966    

DOI:10.1121/1.2021646

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The present work was undertaken in order to provide further evidence about the role played by the physiological and phonological factors in vowel lengthening before voiced consonants. Previous experiments compared cross‐linguistically different consonantal contexts and syllabic types, but, with respect to Spanish disregarded neutralization in final syllable position. Two male adults recorded nonsense bisyllabic words and two other speakers recorded meaningful frequent words where the opposition voiced/voiceless was spontaneously neutralized. Results showed that in open and closed syllables of nonsense utterances (average ratios: 1.4 and 1.23, respectively) vowels are shorter before voiceless consonants than before voiced. In meaningful words, vowels presented longer duration before voiced realizations (20%) of lengthening. However, for nonsense utterances, higher values were obtained and we can assume that this difference is indicating some phonological effect. The lengthening value observed in meaningful words seems to represent more closely the physiological effect.

ISSN:0001-4966    

DOI:10.1121/1.2021654

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Because identification of vowels was not affected by reverberation, possible changes in perception were assessed in a paired comparison paradigm. Fifteen English vowels and diphthongs recorded with and without reverberation (T= 1.2 s) were paired with each other. Ten normal‐hearing subjects made similarity judgments using a scale from 1 to 7. Response matrices for the two conditions were analyzed using multidimensional scaling procedures. A three‐dimensional solution was sought for the data on the basis of the experimental conditions and results of previous studies. Three‐ and two‐way analyses were performed using a ALSCAL subroutine. Both with and without reverberation, the first two dimensions were identified as back‐front and low‐high, confirming the results of previous studies. The third dimension was identified as long‐short while others interpreted it as tensness, openness, or left it unidentified. In both three‐ and two‐way analyses, the shifts in stimulus configuration between test and retest and between reverberant and nonreverberant solutions were of the same order. Therefore, we concluded that reverberation did not contribute significantly to the perceptual distances among vowels and diphtongs. [Supported by NIH.]

ISSN:0001-4966    

DOI:10.1121/1.2021659

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Thus far synthesized speech has been reported by phonetically naive listeners as sounding “metallic” or “as if the speaker had a cold.” One of the explanations for the above is that the simulation of nasal coupling is not close enough to natural speech. We report on research on diphone synthesized utterances (Dixon and Maxey, 1968). In order to simulate a better set of nasalized vowels in synthesized speech, a new set of diphones was created to replace the original ones in those cases in which there is a nasal consonant in the immediate vicinity. These new diphones were the result of hand‐painting single nasal formants in addition to the regular formant frequencies found in the original diphones. Utterances made of both the new and old sets of diphones were played to phonetically naive listeners. Results on naturalness judgments and on intelligibility will be presented.

ISSN:0001-4966    

DOI:10.1121/1.2021661

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

In the course of our research on sound localization we have measured direction‐dependent pinna transfer functions of eight observers. The magnitudes of these functions have peaks and valleys that vary in spectral locus across subject and across source location. We addressed the question of whether these spectral patterns contain sufficient information for accurate localization of sounds in space. We used standard multivariate statistical techniques to develop a model of sound localization based on pattern recognition principles. A Bayesian classification procedure is employed to make a decision as to the most probable source location. The errors made by this procedure are compared to the errors made by subjects when judging source location in free‐field listening conditions. Preliminary results are extremely encouraging. The source positions for which the model makes errors match quite well those for which the subjects make errors. [Work supported by NSF and NIH.]

ISSN:0001-4966    

DOI:10.1121/1.2021664

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Psychophysical detection thresholds were obtained at the thenar eminence and volar forearm using 16 sinusoidal frequencies between 15 and 700 Hz. A small (0.008 cm2) contactor was used, which preferentially excites non‐Pacinian (NP) subsystems. Measurements were made using carefully controlled (± 0.5 °C) skin surface temperatures of 15°, 20°, 25°, 30°, 35°, and 40 °C to enhance or degrade the subsystem responses. The results show several frequency characteristics that cannot be ascribed to activity in the Pacinian system, but do conform to electrophysiological measurements of Ruffini capsules, Meissner corpuscles, and Merkel cells. When threshold values are averaged across temperatures, the resultant curve is approximately flat. The results suggest that the NP system is probably composed of more than a single receptor type and that well‐controlled skin temperature is necessary for the precise measurement of vibrotactile sensation.

ISSN:0001-4966    

DOI:10.1121/1.2021669

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The Diffuse Field Theory of sound propagation indoors, embodied in the formula,[Lp = Lw + 10 log(Q/4πr2 + 4/A)], does not work well for typical furnished rooms in dwellings and offices. An alternative simple empirical relationship has been found that predicts with considerable accuracy the sound pressure level in such rooms, based on the sound power level of the source, the room volume, the frequency, and the distance from the source:Lp = Lw − 10 log r(ft) − 5 log V(cu ft) − 3 log f(Hz) + 25 (dB). If this new relationship is accepted, there are serious implications for our current standard test procedures for field measurements in occupied buildings. Since the room absorptionAdoes not appear explicitly in the formula, the customary normalization with terms like 10 logAin transmission loss and impact noise field tests is probably incorrect. In addition, since no uniform reverberant sound field occurs in normally furnished dwelling and office spaces, it is not clear what one ought to measure for the receiving‐room sound pressure level in field tests of transmission loss, noise reduction, and impact noise. [Work supported by ASHRAE.]

ISSN:0001-4966    

DOI:10.1121/1.2021680

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The Boltzmann‐Ehrenfest principle of adiabatic invariance is applied to a nonlinear system consisting of a self‐constrained finite amplitude acoustic wave propagating in a solid. The results predict the existence of an acoustic radiation stress having two source components. One component is associated with the stress nonlinearity of the solid and is obtained from the adiabatic variation in a parametrized natural wave velocity. The second component results from the variation in the first‐order nonlinear term in the virial theorem expansion and gives rise to an acoustic radiation‐induced static strain. Both components depend directly on the energy density of the propagating wave but are opposite in sign. The coefficient which couples the radiation‐induced static strain to the energy density is the acoustic nonlinearity parameter which characterizes the nonlinearity of the wave equation.

ISSN:0001-4966    

DOI:10.1121/1.2021683

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP