摘要:

Much past research has been devoted to deciding, for any given speech segment, whether it is “voiced” or “voiceless.” In reality, however, speech often combines both glottal and supraglottal excitation, so that such a binary classification can be essentially invalid. We have begun a study of speech produced with mixed excitation with the two major goals of (1) determining the best analytic tools for this type of analysis and (2) examining a variety of real and modeled speech signals for their excitation characteristics. Initial research strategies and preliminary results will be discussed. [Research supported by NSA.]

ISSN:0001-4966    

DOI:10.1121/1.2021746

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

A text‐to‐speech system has three linguistically related components that each affect the intelligibility of the speech it produces. These three components are: (1) the quality of the individual sounds and how they fit together (or how the algorithm fits them together), (2) the accuracy of the output of the ASCII to phonemic unit algorithms and/or rules, and (3) the quality of the prosodic algorithms, including work‐stress and pausegroup implementations. Text‐to‐speech development, therefore, should involve the testing of each of these components for the purposes of maximizing the accuracy and acceptability of each component's output. This presentation will therefore discuss an implementation of testing algorithms for phonemic construction intelligibility, for ASCII‐to‐phone accuracy, and for prosodic naturalness for the development of a text‐to‐speech system for the T.I. Professional Computer.

ISSN:0001-4966    

DOI:10.1121/1.2021798

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

In general, the hearing‐impaired children can recognize the voices of their teachers better than those of normal persons. The purpose of this study is to make clear the difference between the teacher's voice and a normal person's. In this study, we analyze the Japanese vowels of the teacher and normal persons, and compare their acoustic characteristics. The formant frequency (F1,F2,F3) and the power of the formant frequency (P1,P2,P3) are chosen as the phonetic features, and we analyze them by using our new automatic formant extractor. As a result of the experiments, there is no difference between the teacher's voice and the normal person's on bothF1 andF3. But theF2 of teacher's /i/ and /e/ is higher than the normal person's. TheF2 of the teacher's /u/ is lower, namely the frequency distances between /i/‐/u/ and /e/‐/o/ ofF2 are larger. BothP2 andP3 of teacher's are higher than those of the normal person's. It is shown by this study that misrecognitions of /i/ and /u/ and /e/ and /o/ are decreased among hearing‐impaired children by the above‐mentioned reason.

ISSN:0001-4966    

DOI:10.1121/1.2021846

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The mechanisms by which intensity is coded in the discharges of single auditory nerve fibers have not been fully determined, although hypotheses involving changes in discharge rate fiber recruitment have been proposed. In this paper, we will review the characteristics of auditory nerve fiber responses that may code for loudness growth and intensity discrimination. Psychophysical dynamic ranges, which are in excess of 100 dB, cannot be accounted for by the 30–40 dB dynamic range displayed by the majority of individual auditory nerve fibers. Recently, however, a subpopulation of auditory nerve fibers has been identified within each characteristic frequency (CF) region. The characteristics of these fibers include low spontaneous activities, a wide range (greater than 70 dB) of thresholds, high sensitivities to changes in intensity (i.e., steep rate‐intensity functions), and dynamic ranges as high as 60–70 dB. These results indicate that the responses of fibers having similar CFs and spanning the normal range of thresholds may account for a large portion of the behavioral dynamic range. Furthermore, intensity discrimination experiments designed to limit the spread of excitation (Hellman, 1974; Viemeister, 1974), suggest that intensity coding does not depend on recruitment of neighboring fibers. Finally, phase‐locking exists for stimulus frequencies below 5 kHz, and phase‐locking thresholds are on the average 15 dB lower than corresponding discharge rate thresholds. Thus, the overall dynamic range associated with auditory nerve responses can account for nearly the entire psychophysical loudness range. Other characteristics of neuronal response, such as input/output nonmonotonicities and synchrony suppression in the coding of multi‐component stimuli, will be discussed.

ISSN:0001-4966    

DOI:10.1121/1.2021892

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The discrimination of intensity plays a central role in Fechnerian theories of the perception of intensity: Perceptual differences between two stimuli are determined by the cumulative number of jnd's which separate the intensities. We review recent research which suggests that this view must be modified to account for the total number of jnd's in the listener's dynamic range or in the range of intensities used in an experiment. Specifically, loudness balance measurements are better predicted if the number of jnd's is normalized by the total number of jnd's in the dynamic range. Resolution between two intensities in identification experiments reflects not only the number of jnd's separating the intensities, but also the total number of jnd's in the stimulus range and the proximity of the intensities to perceptual anchors. These results indicate the need for complementing our increasing understanding of intensity discrimination with an improved understanding of perceptual anchors and the limits of the dynamic range.

ISSN:0001-4966    

DOI:10.1121/1.2021932

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

A comprehensive research program has been conducted by NASA Langley Research Center to develop a fundamental understanding of human discomfort response to combined noise and vibration typical of that experienced within air and surface transportation systems. Results of this research program produced an empirical model of passenger ride comfort for use in the prediction and/or assessment of passenger ride comfort. The model is based on subjective ratings from more than 3000 persons who were exposed to controlled combinations of noise and vibration in the passenger ride quality apparatus at Langley Research Center. This model has the unique capability of transforming individual elements of a vehicle's noise and vibration environment into subjective units and then combining the subjective units to produce a single discomfort index typifying passenger acceptance of the environment. This paper discusses the approach and basic elements of the NASA ride comfort research program, describes the resultant model and its applications to real vehicles, and discusses a portable ride quality meter that is a direct hardware/software implementation of the NASA ride comfort model.

ISSN:0001-4966    

DOI:10.1121/1.2021984

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Multiple scattering theory is used to study the propagation of compressional waves in systems comprised of spherical solid grains embedded in an inviscid fluid. In the case of primitive ordered cubic suspensions the problem reduces to a system of coupled equations whose solution is shown to have the form predicted by Biot; i.e., a singlegeometricalparameter α, characterizes the suspension. By contrast, in disordered suspensions, we show that the Biot formula is not rigorously applicable. We argue that a proper theory must treatfluctuationsin the environment of a typical grain. (This is analogous to calculating corrections to the local field in a polarizable media.) These effects introduce dependence of the long wavelength sound speed on (1) the radial (i.e., pair) distribution function and (2) higher scattering multipoles. The extent to which various approximation schemes include these fluctuations is discussed and illustrative calculations for the case of densely packed composites are presented. We point out that the available acoustic data are based on suspensions in which the fluid‐solid density contrast is not great enough to distinguish between competing approximations.

ISSN:0001-4966    

DOI:10.1121/1.2022031

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Numerical methods for predicting acoustic scattering from cylindrical shells generally consist of large finite element models of the shell coupled with finite element or integral representations of the fluid. In order to reduce the computational effort, the fluid can be represented by doubly asymptotic approximations [T. L. Geers and C. A. Felippa, J. Acoust. Soc. Am.73,1152–1159 (1983)]. The accuracy of first‐and second‐order DAA's is demonstrated for the two‐dimensional scattering problem of a plane acoustic wave incident on a thin cylindrical shell with and without an attached oscillator. Quantities compared to the exact solutions are fluid modal impedance and farfield radiated pressure. By appropriately adjusting a parameter value in the second‐order DAA, the impedance and pressure can be determined with reasonable accuracy. The first‐order DAA is demonstrated to be not as accurate. The effect of the oscillator on the radiated pressure is also discussed.

ISSN:0001-4966    

DOI:10.1121/1.2022081

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The Parabolic Equation (PE) has applications in many different scientific fields such as electromagnetics, optics theory, quantum mechanics, plasma physics, seismology, underwater acoustics, etc. This presentation centers on a discussion of the parabolic equation approximation as applied to underwater acoustic wave propagation—past, present, and future directions. A review will be given of past contributions. Recent developments are highlighted. Looking ahead we discuss what the parabolic equation method can do in order to stimulate future research and development, as well as applications. Intensive computations with respect to the parabolic equation implementation will also be discussed.

ISSN:0001-4966    

DOI:10.1121/1.2022120

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Ocean acoustic problems are very complicated by nature and require large scale computations. Recent computer technology advances have produced very fast, inexpensive pipelined array processors. These processors allow the efficient, cost effective solution of complicated problems. This presentation begins with a demonstration of a two‐dimensional model ocean acoustic long range propagation problem and discusses its solution on both a conventional sequential computer and a pipelined array processor. The next step of the application of multi‐array processors is presented. A three‐dimensional model ocean acoustics problem is chosen as a sample problem for such multiprocessors. [Work supported by ONR.]

ISSN:0001-4966    

DOI:10.1121/1.2021699

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP