摘要:

The purpose of the present study was to investigate kinematic characteristics of the speech of children and adults under three speaking conditions. The effects of requiring subjects to produce speech stimuli were studied as they spoke: (a) in a normal manner; (b) at a faster than normal rate; and (c) while holding a bite block between their molars to restrict mandibular movement. Using a strain gauge monitoring system, superior–inferior lip and jaw movement data were collected from 24 subjects—six in each of three groups of normally developing children and an adult control group. For the normal condition, it was found that net peak velocity (i.e., the sum of the peak velocities of the individual articulators) was quite comparable among the three groups of children and the adults. Net peak velocity increased significantly for all four groups of subjects when they spoke at a fast rate, but it did not increase significantly in the bite block condition. For most measures, there were typically no differences in peak velocity across the various speaking conditions when comparing the three groups of children to one another. In general, articulatory displacement data showed patterns quite similar to those of the peak velocity data. In addition to the displacement and peak velocity data, pilot data are discussed concerning temporal properties of articulatory phases and also concerning maximum, nonspeech articulatory gestures.

ISSN:0001-4966    

DOI:10.1121/1.394843

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

To investigate the extent and locus of integral processing in speech perception, a speeded classification task was utilized with a set of noise‐tone analogs of the fricative‐vowel syllables /fæ/, /∫æ/, /fu/, and /∫u/. Unlike the stimuli used in previous studies of selective perception of syllables, these stimuli did not contain consonant–vowel transitions. Subjects were asked to classify on the basis of one of the two syllable components. Some subjects were told that the stimuli were computer generated noise‐tone sequences. These subjects processed the noise and tone separably. Irrelevant variation of the noise did not affect reaction times (RTs) for the classification of the tone, and vice versa. Other subjects were instructed to treat the stimuli as speech. For these subjects, irrelevant variation of the fricative increased RTs for the classification of the vowel, and vice versa. A second experiment employed naturally spoken fricative‐vowel syllables with the same task. Classification RTs showed a pattern of integrality in that irrelevant variation of either component increased RTs to the other. These results indicate that knowledge of coarticulation (or its acoustic consequences) is a basic element of speech perception. Furthermore, the use of this knowledge in phonetic coding is mandatory, even in situations where the stimuli do not contain coarticulatory information.

ISSN:0001-4966    

DOI:10.1121/1.394844

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

In the present study, speech‐recognition performance was measured in four hearing‐impaired subjects and twelve normal hearers. The normal hearers were divided into four groups of three subjects each. Speech‐recognition testing for the normal hearers was accomplished in a background of spectrally shaped noise in which the noise was shaped to produce masked thresholds identical to the quiet thresholds of one of the hearing‐impaired subjects. The question addressed in this study is whether normal hearers with a hearing loss simulated through a shaped masking noise demonstrate speech‐recognition difficulties similar to those of listeners with actual hearing impairment. Regarding overall percent‐correct scores, the results indicated that two of the four hearing‐impaired subjects performed better than their corresponding subgroup of noise‐masked normal hearers, whereas the other two impaired listeners performed like the noise‐masked normal listeners. A gross analysis of the types of errors made suggested that subjects with actual and simulated losses frequently made different types of errors.

ISSN:0001-4966    

DOI:10.1121/1.394845

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

There are very few exact solutions available for wave propagation in plane‐layered materials that are pierced by a cylindrical hole. This is unfortunate since these problems occupy a central role in geophysics. Exact solutions for the cases of an empty hole and an infinitely rigid hole, where the geometry is separable so that the classical transform method is applicable, are presented. It is hoped that the exact solutions presented herein will provide a check on more general numerical methods.

ISSN:0001-4966    

DOI:10.1121/1.394793

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

Remarks concerning the physical mechanism of the acoustical pressure wave scattering by thin elastic spheroidal shells are given.

ISSN:0001-4966    

DOI:10.1121/1.394794

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

This letter to the editor is a reply to N. D. Veksler’s criticisms [J. Acoust. Soc. Am.81, 777–779 (1987)] of the article ‘‘A comparison of acoustical scattering from fluid‐loaded elastic shells and soft objects’’ [M. F. Werby and L. H. Green, J. Acoust. Soc. Am.76, 1227–1230 (1984)].

ISSN:0001-4966    

DOI:10.1121/1.394795

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

Acoustical scattering from spherical shells has been studied extensively in the literature and is a highly developed and well‐understood area. In contrast, scattering from nonspherical, three‐dimensional objects has not been studied extensively due to theoretical and computational difficulties. The purpose of the work presented here is to study backscattered echoes (form functions) from submerged spheroidal elastic shells for end‐on incident plane waves for several aspect ratiosL/Dand to compare the results with the well‐studied spherical analog (Lis the length andDthe width of the object). The frequency range studied in terms ofkL/2 (wherekis the wavenumber of the incident field) goes fromkL/2=3 tokL/2=15 and the aspect ratio varies from 1.5 to 3.0. Two values for shell thickness studied are for 0.1% and 1.0% of the semimajor axis, with the constraint that the inner surface of the shell is spheroidal. A remarkable similarity is noted between the form functions of the spheroids and the shells. This correspondence can be shown to be deduced from phenomenological expressions (due to Werby and Gaunard, ‘‘Proceedings of the 1985 Pressure Vessels and Piping Conference,’’ New Orleans, LA, 23–26 June 1985) for resonance locations and offers a simple means to predict the locations of end‐on resonances for the more intractable problem of higher aspect ratio spheroids.

ISSN:0001-4966    

DOI:10.1121/1.394796

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

Previously unpublished results from a 1978 acoustic propagation experiment in the Southwest Pacific Ocean to the east of New Zealand are combined with earlier data to produce measured values of the water column attenuation over the frequency range 32–1000 Hz. The attenuation values so obtained compare well with a modified Thorp formula having a boron relaxation term and a scattering term generally consistent with earlier estimates for the region.

ISSN:0001-4966    

DOI:10.1121/1.395114

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

In a recent paper by Narasimhanetal. [J. Acoust. Soc. Am.79, 382–385 (1986)] a method is proposed for the determination of object range distance for planar holographic systems by phase unwrapping the spectral distribution along the major axes. In this letter, an alternative approach is introduced to improve the range distance estimation process. This technique simplifies the procedure by utilizing the Fourier transformation symmetry properties associated with the real object distribution and propagation transfer function. The computation complexity can be significantly reduced because of the elimination of the complicated computing and phase unwrapping steps. In addition, the accuracy of the distance estimation is improved by using the complete two‐dimensional spectral distribution instead of only the variation along the axes.

ISSN:0001-4966    

DOI:10.1121/1.394797

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP

摘要:

This letter presents an experiment in acoustics to be used in a laboratory course for advanced undergraduate or beginning graduate students in physics or engineering. It describes the equipment used and the effect of reflection from a plate immersed in water on the driving‐point impedance of a small sonar transducer placed at the air–water surface above the plate.

ISSN:0001-4966    

DOI:10.1121/1.394798

出版商:Acoustical Society of America    

年代:1987

数据来源: AIP