摘要:

Tape recordings made in the helium‐oxygen atmosphere of the U. S. Navy'sSEALAB IIhave been analyzed by spectrographic techniques. The divers breathing this gas mixture have an unusual voice quality often characterized as “Donald Duck” speech. The Sealab experiment permitted speech analysis of divers living in such an atmosphere for several days. A preliminary study of the recorded data has led to the following observations: (1) formant shifts are responsible for the unusual quality of the helium‐oxygen speech; (2) the formant shifts are nonlinear—the frequency shift of the first formant is greater than the frequency shifts of the higher order formants; (3) relative formant amplitudes are often changed radically; (4) pitch or fundamental frequency changes are not significant; (5) after several days in this new atmosphere, changes occurred in the speech quality that made it sound more natural. These changes most likely have been affected by modifications of the vocal‐tract gestures.

ISSN:0001-4966    

DOI:10.1121/1.1942790

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Previous analysis of helium speech has shown that the peculiar characteristic of this speech is due primarily to changes in formant frequencies of the speaker. Even though some change does take place in the fundamental pitch frequency of the speaker, this effect is small and usually can be neglected. Computation of the resonant frequencies of the vocal tract as a function of the gas mixture occupying the tract gives a reasonable estimate of the changes that take place in the formant frequencies. A modified self‐excited channel vocoder was designed to restore approximately the normal values of the talker's formant frequencies while preserving his fundamental pitch frequency. This “formant‐restoring‐vocoder” (FRV) separates the spectral energy of the helium speech into a number of narrow bands that then amplitude‐modulate lower‐frequency pitch harmonics derived directly from the hedium speech. The lower‐frequency harmonics are separated by bandpass filters that are proportionately narrower and lower in frequency than the spectral‐energy separating filters. Helium speech fromSEALAB IIwas processed by an FRV simulated on a digital computer. Results of several simulations indicated that considerable improvement in naturalness and intelligibility of helium speech can be achieved.

ISSN:0001-4966    

DOI:10.1121/1.1942791

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Detailed discussion of the performance of company programs that generate the phonetic transcriptions of lexed items monosyllabic according to theShorter Oxford Dictionaryfor each of five distinct sets of transcriptions is given in this paper. [B. V. Bhimani and R. Mitchell, J. Acoust. Soc. Am.38, 934(A) (1965).] Programs that are “optimal” in the sense that they yield transcriptions from the orthographic forms of lexed items for each dialect recognized by each of the five sources, without regard to actual citations by the authorities, have been written. Programs that are ldquo;optimal” in the sense that they yield transcriptions for at least one of the recognized dialects in each of the five sources have also been prepared. A program has also been written that is optimal in the sense that it generates the transcriptions of lexed items for at least one of the dialects in all five sources at once. Comparative analysis of both the performance and the results of these computer programs is given. [Work supported by Lockheed Independent Research.]

ISSN:0001-4966    

DOI:10.1121/1.1942798

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Measurements of surface reverberation made in the North East Pacific are presented. Sounds produced by 1‐lb explosive charges detonated at depths between 175 and 1000 ft yielded scattering strength results in the frequency range 320–10 240 cps, and between grazing angles of 2° and 75°. The scattering‐strength values are generally lower than those reported in the literature. Although the range of wind speeds over which the data were gathered was not great, a wind‐speed dependence is indicated, as is a frequency dependence. A program of surface‐wave measurement in conjunction with surface‐reverberation measurement has been initiated in an effort to resolve the variation in the results obtained by different investigators.

ISSN:0001-4966    

DOI:10.1121/1.1942805

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

A mathematical model considering reflection as a reradiation phenomenon has been constructed. The model allows computation of the spectrum and waveform of a reflected pulse in terms of the incident plane‐wave pulse or its spectrum, the reradiation characteristics of the reflector, the incident direction, and the reradiation direction. Bottom reflection of sonic pulses in an isovelocity medium has been considered in terms of this model and temporal and spectral distortions have been calculated. The theory of Cron and Nuttall [J. Acoust. Soc. Am.37, 486–492 (1965)] is shown to be a special case of the present theory.

ISSN:0001-4966    

DOI:10.1121/1.1942812

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The quantitative determination of nerve‐cell populations of brain structures after degeneration of the cell bodies following the placement of appropriate lesions constitutes a powerful method of determining structural relations in brain. The features of the ultrasonic method of lesion production that make it particularly useful in such studies are briefly reviewed, and lesions in specific structures pertinent to the quantitative study of the mammillary complex of cat brain are illustrated. The reproducibility, for the methods presently employed, of neuronpopulation ratios for related structures now under investigation is discussed, and the use of such data to determine neuronal circuitry relations is illustrated by a specific example. This presentation does not require prior neuroanatomic knowledge as a basis for its understanding. Its purpose is to illustrate the principles of deciphering quantitative relations of connections between sets of nerve cells and this can be achieved without prior knowledge of the system to which the methods are applied.

ISSN:0001-4966    

DOI:10.1121/1.1942816

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The purpose of this investigation was to determine what new organic compounds or high concentration of a particular organic species can be formed by exposure of coal derivatives to ultrasonic energy. Tetralin, 1‐methylnaphthalene, and pyridine were used as model compounds. Gaseous and solid reaction products resulting from the ultrasonic irradiation of the above coal derivatives were determined, using mass spectrometry. Products from the irradiation of tetralin were studied as a function of time, atmosphere, and sample size. The sonolysis of tetralin producedC2H2, HCN,CH4, H2, CO, andCO2, depending upon the experimental conditions. The cleavage of organic liquids by ultrasonic cavitation in the absence of water, recently reported by Weissler, Pecht, and Anbar, was also observed in this study.

ISSN:0001-4966    

DOI:10.1121/1.1942818

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The use of the computer as a tool for the creative musician presents an entirely new set of initial conditions for the exploration and organization of sound. The art of relating the parameters of electrical waveforms to sound, the understanding of computers and coding, and the sensitivity of the artist are the basic elements that develop within a single individual for creative expression. To generate complex sounds requires a large amount of data‐processing. To achieve a high degree of flexibility requires a relatively small amount of input data. These two conditions can be met if the coding techniques relate the inherent characteristics of the computer to musical parameters, and if the coding techniques are geared to individual style and requirements. An alphabet based on the parameters of waveforms in contrast to a general dictionary of musical sounds offers a wider range of possibilities for expression. Some computer‐music samples are presented.

ISSN:0001-4966    

DOI:10.1121/1.1942826

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

At the November 1965 meeting of the Society [J. Acoust. Soc. Am.38, 928(A) (1965)], we presented the results of a series of unsuccessful attempts to replicate the findings of Green, Birdsall, and Tanner [J. Acoust. Soc. Am.29, 523–531 (1957)] on detection versus duration. Since then, still using a fixed‐bandwidth filter, but by changing the time constants of the detector, we have come much closer. Like them, we have employed a continuous masker and a constant value ofE/Noand our new data yield a close fit to theirs. The filter is followed by a linear (half‐wave) detector and by an integrator with a decay time of 100 msec. A replication of the experiment, this time employing a square‐law rectifier (energy detector), but using the same integration time constants, yielded reasonably similar results. [Work supported through a contract with the U. S. Bureau of Ships and a grant from the National Aeronautics and Space Administration.]

ISSN:0001-4966    

DOI:10.1121/1.1942829

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

A probe‐signal method was developed and used to study differential detection as a function of the signal frequency when observers were instructed to listen for signals of a single fixed frequency. All signals were presented in a continuous background of noise, with a two‐alternative temporal forced‐choice procedure. Response characteristics were found that are consistent with the idea of an underlying frequency‐selective mechanism similar to a fairly narrow bandpass filter. A discussion is given of various applications of the method to produce data that will identify the strategies that an observer uses to process certain auditory stimuli selectively. [Work supported by the National Institute of Neurological Diseases and Blindness, National Institutes of Health, Public Health Service, U. S. Department of Health, Education, and Welfare.[

ISSN:0001-4966    

DOI:10.1121/1.1942833

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP