摘要:

Simultaneous recordings of voice and cricothyroid activity during speech production by one speaker of Hindi were made. The subject produced utterances containing stops, affricates, and fricatives. All utterances were embedded in carrier sentences. The results show markedly higher levels of cricothyroid activity for the voiceless stops, affricates, and fricatives than for their voiced cognates. This suggests that the cricothyroid may play some role in maintaining voiced versus voiceless contrast in consonant segments. It does so at least in this subject.

ISSN:0001-4966    

DOI:10.1121/1.2018486

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

Previous research has shown that lip and jaw movements can vary dramatically with speaking rate. However, few studies have explored lip and jaw movements over a range of contrived speaking rates. The purpose of this investigation was to examine kinematically movement parameters associated with six different rates of speaking (1–6 s). The upper lip, lower lip, and jaw vertical amplitudes of a naive male speaker were transduced via a strain gauge system and recorded concurrent with the speaker's utterances. Consonant‐vowel syllables composed of /m, p, k, w/ in combination with the vowels /i/ and /æ/ served as the speech sample. Desired rates of production were obtained by training the subject to synchronize his productions with an audiovisual timing device. The results demonstrated generally increased upper lip amplitudes and reduced jaw amplitudes as the rate of speaking increased. More importantly, lower lip velocity was observed to increase systematically from 1 to 3 s but decreased precipitously at 4 s, and thereafter increased in a pattern similar to that found for the slowest rates. This apparent reorganization at a consistent rate corresponded to voicing and movement variability also associated with an utterance rate of four syllables per second. Discussion will focus upon these variables.

ISSN:0001-4966    

DOI:10.1121/1.2018491

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

The appearance of new formants in the vowel spectrum when the nasal tract is connected with the oral tract, has been studied. With a numerical harmonic simulation of the transmission‐line analogy taking into account all losses (radiation, heat, viscosity, wall vibration), the variation of the input impedances with frequency looking into the three tubes from the coupling point of nasal tract (calledXnandXbp) have been calculated. With these data, we can explain graphically the formation of the peaks and dips on the spectrum. From circuit analogy, the nasal formantFnis the frequency where the reactance looking into the nasal tract from the coupling point is infinite, and the nasal zeroAnis where this reactance is zero. The intersections of a branch of −Xnand two branches ofXbpare considered as the two “formants” newly created by splitting of the original formant by the zeroAn. These peaks can be defined as: (1) The shifted frequency of the original formant (termed “the primary formant”); (2) the newly created formant accompanying (termed “the secondary formant”). This formant was generally referred as “nasal formant.” Taking into account all kinds of losses leads, sometimes, to the decrease of the number of intersections (of −XnandXbp) when comparing with results obtained without losses. The zeros found in the spectrum of a nasalized vowel at the nasal antiformant frequencies are greatly diminished by high losses in this tract.

ISSN:0001-4966    

DOI:10.1121/1.2018497

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

Simulation, in the time domain, of a complete source‐vocal tract model including the frequency‐dependent losses is quite impossible. But, in order to study the volume flow at the level of the glottis in the best conditions, we can use a two‐mass model loaded by a circuit representing the impedance of the vocal tract. The spectrum of the volume flow has been calculated when the model is loaded by the representative impedance of the vocal tract and when court circuiting. The mean value of the glottal impedance has been determined from comparisons between both spectrums. This value has been measured for different frequencies corresponding to several vowel formants. Formant frequency variations due to the glottal impedance and synchronization effects (pointed out by amplitude variations around formant frequency} can be observed on the source spectrums. Some of these results are in agreement with the real data. Some others have to be verified. In conclusion, and with other results elsewhere reported, it seems that a two‐mass model of the vocal cords is, until now, a good approximation of the real behavior of the glottal source.

ISSN:0001-4966    

DOI:10.1121/1.2018498

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

We have adapted our model of surface‐generated noise in a stratified lossy ocean to the case of low‐frequency wind‐generated noise produced in deep water by turbulent pressure fluctuations in the atmosphere. The model assumes a random pressure distribution at the surface and includes the effects of sound‐speed profile and bottom characteristics. Using Wilson's source levels [J. H. Wilson, J. Acoust. Soc. Am.66,1499–1507 (1979)] we have calculated the noise level as functions of frequency and depth and compared the results with measured data. We show these results along with calculations of the spatial coherence function, which differs significantly from the standard deep‐water result. Finally, we present calculations of the effective surface area, that is, the area of the surface centered above the receiver which contributes most of the noise intensity. We show that this quantity is dependent on receiver depth.

ISSN:0001-4966    

DOI:10.1121/1.2018501

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

A sampling problem resulting in slow convergence of noise levels predicted by a Monte Carlo type low‐frequency underwater acoustics noise model, SIAM II, led to the development of a simple analytical ambient noise model, called CNOISE. The inputs to the model are azimuthal sector geometry about a receiver, ship counts in range‐sector bins, transmission loss curves for each sector, and ship source levels. The outputs available from the model include horizontally directional and omnidirectional ambient noise levels. The major advantages of this model include: Significantly increased speed relative to Monte Carlo noise models, and analytical solution that lends itself to straightforward analysis and implementation, and the avoidance of the sampling problems which appear to plague Monte Carlo models. Comparisons of noise levels predicted by other models (BEAMPL, SIAM II, and FANM) have shown very good agreement.

ISSN:0001-4966    

DOI:10.1121/1.2018507

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

Simultaneous production of two pure tones with frequenciesf1andf2is associated both with auditory beats (rapid fluctuations in loudness) and with audible difference tones. Since the same frequencyf1−f2is encountered in both cases, students tend to think a difference tone is nothing more than a beat phenomenon whose frequency is high enough to be in the audible range. But, in fact, these are two entirely distinct effects. I will discuss how to convincingly present this difference at three levels: (1) Simple theory of added and multiplied waveforms, (2) visual demonstration with oscilloscope plug‐in Fourier analyzer, and (3) audible demonstration. These show that our ears can literally hear and distinguish two separate phenomena.

ISSN:0001-4966    

DOI:10.1121/1.2018511

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

A common element among several proposed speech perception models is that an acoustic representation of the speech signal persists briefly in memory prior to phonetic processing. It is also commonly hypothesized that with the passage of time the auditory signals are degraded. These hypotheses were tested in a perceptual experiment in which subjects were presented short segments of vowels for identification. A single glottal pulse from each of the vowels /ɑ, i, I, æ, ε,/ was excised from natural speech and repeated to produce three types of stimuli: two contiguous glottal pulses, four contiguous glottal pulses, and two contiguous glottal pulses followed by two more contiguous glottal pulses with interspersed silences of 10, 20, 40, 60, 80, 120, 240, 480, 1000, and 2000 ms. The stimuli for all vowels and types were randomized and presented to subjects. As expected, the four contiguous glottal pulse stimuli gave better recognition scores than the two contiguous glottal pulse stimuli. It was predicted that as the interstimulus silent intervals increased for the third class of stimuli that the recognition scores would approach those of the two glottal pulse stimuli. In general, this hypothesis was confirmed except for an apparent perceptual recovery interval between 60 and 240 ms.

ISSN:0001-4966    

DOI:10.1121/1.2018517

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

Adaptive test procedures were used to estimate: (1) boundaries between perceptual “categories” of a labeling, or identification, task and (2) the just‐discriminable difference to each side of the midpoint of a 13‐item /ba/‐/da/‐/ga/ continuum of 4‐formant, synthesized syllables (AX task). At the locus of the /ba/‐/da/ boundary: (1) both 10‐year olds and adults had significantly better discrimination than 6‐year olds; (2) 10‐year‐olds' categorical boundaries were significantly different from those of 6‐year olds; and (3) only adults showed a significant difference between the discrimination limen and the boundary between “categories.” At the locus of the /da/‐/ga/ boundary, performance of 6‐year‐olds differed significantly from adults'. These results were obtained even though all Ss scored approximately 100% correct on a speech discrimination test—WIPI for children and W‐22 for adults—and parallel results obtained on a monosyllabic word perception task [Elliott, L. L.et al., J. Acoust. Soc. Am.66,12–21 (1979)]. [Supported in part by BEH, NINCDS, and NSF.]

ISSN:0001-4966    

DOI:10.1121/1.2018038

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP

摘要:

The cerebellum of a vertebrate not only receives signals from the motor areas of the cerebral cortex but also receives different impulses indirectly from almost all sensory receptors. WithEptesicus fuscus, we studied the response properties of cerebellar neurones to acoustic stimuli (40 ms duration, 0.5 ms rise‐decay time). Single neurones responding to auditory stimuli could be isolated from rather large areas of the bat's cerebellar vermis and hemispheres. They were usually spontaneously inactive and discharged either tonically or phasically. These units had latencies between 4 and 13 ms and best frequencies between 22 and 77 kHz. TheQ10‐dB values of their triangular tuning curves were between 1.4 and 16.6 with the majority below 10. Minimum thresholds were between 12 and 65 dB SPL. When acoustic stimuli were delivered through the earphones, tuning curves measured from each ear alone were nearly identical in shape and best frequency. At present, we do not know whether the units we studied were exclusively auditory or multimodal neurones [Work supported by DFG of West Germany and NSF of USA.]

ISSN:0001-4966    

DOI:10.1121/1.2018042

出版商:Acoustical Society of America    

年代:1980

数据来源: AIP