摘要:

In spite of various claims for the presence and functional significance of brainstem reflexes in phonatory control, very little is known about these reflexes in humans. The present study was aimed at studying auditory‐laryngeal reflexes in human subjects during sustained phonation. Fourteen subjects sustained phonation at constant voice pitch and voice intensity while receiving auditory stimulation with clicks of different intensity levels. Electromyographic (EMG) recordings from the cricothyroid muscle were obtained in two of the subjects. The voice signal was transduced with a throat microphone and bandpass filtered to isolate the fundamental frequency (F0). The filtered signal was fed to a frequency meter, which yielded a voltage proportional toF0. ThisF0 voltage and the rectified EMG were signal averaged relative to the click. Short‐latency changes inF0 (50 ms) and in cricothyroid EMG (11 ms) were observed in response to auditory stimulation. The magnitude of the EMG andF0 responses were well correlated with each other and with the intensity of the stimulus. The EMG response did not habituate with repeated stimulation. The neuromuscular origins of the auditory‐laryngeal reflexes and their significance to phonatory control are discussed.

ISSN:0001-4966    

DOI:10.1121/1.388812

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Running spectral displays derived from linear prediction analysis were used to examine the initial 40 ms of stop‐vowel CV syllables for possible acoustic correlates to place of articulation. Known spectral and temporal properties associated with the stop consonant release gesture were used to define a set of three‐time‐varying features observable in the visual displays. Judges identified place of articulation using these proposed features from running spectra of the syllables /b,d,g/ paired with eight vowels produced by three talkers. Average correct identification of place was 88%; identification was better for the male talkers (92%) than the one female talker (78%).Posthocanalyses suggested, however, that simple rules could be incorporated in the feature definitions to account for differences in vocal tract size. The nature of the information contained in linear prediction running spectra was analyzed further to take account of known properties of the peripheral auditory system. The three proposed time‐varying features were shown to be displayed robustly in auditory filtered running spectra. The advantages of describing acoustic correlates for place from the dynamically varying temporal and spectral information in running spectra is dicussed with regard to the static template matching approach advocated recently by Blumstein and Stevens [J. Acoust. Soc. Am.66, 1001–1017 (1979)].

ISSN:0001-4966    

DOI:10.1121/1.388813

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The sensitivity of speech discrimination tests is defined as being large if a small change in experimental conditions causes a large and repeatable change in test score. The aim of this paper is to investigate ways by which test sensitivity can be maximized. The effect of test difficulty on sensitivity is examined by the use of a model based on signal detection theory and subjective similarity rating concepts. For several sets of assumptions about the parameters underlying the perceptual processes, the model indicates that test difficulty should be in the range 73% to 87% to achieve the maximum sensitivity with speech tests using between four and eight response foils. The model results also indicate that the sensitivity increases with the number of response foils. When the variation of test reliability with test difficulty is taken into account, the test difficulty which maximizes the sensitivity/reliability trade‐off lies in the range 85% to 90%. It is argued that irrespective of the optimum test difficulty, a maximally sensitive test will contain items equal to one another in difficulty.

ISSN:0001-4966    

DOI:10.1121/1.388815

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The sounds from certain types of gongs show a frequency shift, up or down, as the vibration decays. In order to understand this nonlinear behavior, we have studied the vibrations of a variety of flat and curved plates under varying amounts of radial tension or compression. Flat plates show a nonlinearity of a hardening type (falling frequency), whereas most curved plates show softening behavior (rising frequency). The degree of the nonlinearity appears to be sufficient to explain the observed frequency shift in the gongs studied.

ISSN:0001-4966    

DOI:10.1121/1.388816

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

In order to study metal fluorides of the fluorite structure at temperatures greater than 650 °K using ultrasonic techniques, several previously reported acoustic bonds were found to be inadequate. DuPont 9770 silver–platinum paste has been found to act as an effective acoustic bond for longitudinal ultrasound in contrast to the usual high temperature oxide acoustic bonds which break because they interact strongly with fluoride materials. Measurements of longitudinal ultrasonic velocities have been made up to 796 °K in [110] oriented CdF2and up to 850 °K in [100] oriented BaF2. In neither of these measurements did the bonds break at the highest temperatures.

ISSN:0001-4966    

DOI:10.1121/1.388817

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

A new method is presented for analysis of the dynamic response of disordered particulate composites. The method consists of computation of the losses due to scattering by inclusions and subsequent application of the Kramers–Kronig relationships to derive the phase velocity of the wave. Explicit expressions are given for a porous elastic medium.

ISSN:0001-4966    

DOI:10.1121/1.388818

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

An elastic solid has, in general, three distinct wave propagation velocities in a given direction. According to a theorem of Fedorov, however, there are only two distinct velocities of propagation associated with an axis of material symmetry greater than binary symmetry. The converse of this theorem is proved herein, namely, that it is only in directions of material symmetry greater than binary symmetry that two distinct velocities occur. This leads to an ordering principle for elastic wave propagation velocities, that is, that the order of the velocities, regarded as functions of the direction of propagation, is invariant.

ISSN:0001-4966    

DOI:10.1121/1.388819

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

Acoustical holographic reconstruction techniques which were developed by Williamsetal. [J. Acoust. Soc. Am.68, 340–344 (1980)] have been simulated on a digital computer. Sound pressure and normal acoustic intensity images are reconstructed and graphically compared with their theoretical values for simple monopole and dual monopole configurations. Sources of error such as wraparound, aliasing, and nonuniform microphone response (magnitude and phase) are investigated. The resolution enhancement afforded by the reconstruction process is also demonstrated.

ISSN:0001-4966    

DOI:10.1121/1.388820

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The extended Lagrange manifold (JWKB) technique is presented to illustrate how it reduces to a straightforward exercise the problem of locating the caustic curve and determining the asymptotic series solution on the caustic formed near a fixed source in a stratified medium moving with a uniform horizontal velocity. The case where the horizontal motion is depth dependent is also discussed. [AIP]

ISSN:0001-4966    

DOI:10.1121/1.388821

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP

摘要:

The velocity of ultrasound at a frequency of 25.1 MHz was measured as a function of concentration, temperature, and time in binary solutions of polyacrylamide with water.

ISSN:0001-4966    

DOI:10.1121/1.388822

出版商:Acoustical Society of America    

年代:1983

数据来源: AIP