摘要:

As an initial step toward a general speech recognition computer program, program was developed to recognize ten English vowels in isolated words of the form |b| ‐vowel‐ |t|. The input to the computer was real‐time spectral data. The program first determined the rough location of the first two formants. The remaining confusions were resolved by (1) finer determination of theF1 andF2 locations by the use of slope and/or valley information, (2) the use of pitch information, and (3) in certain cases the determination of the position ofF3. The over‐all score for 21 subjects (11 male and 10 female) was 88%. By the use of duration information, the score was raised to 93%.

ISSN:0001-4966    

DOI:10.1121/1.1907653

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

It has been found to be extremely difficult to isolate phonemic elements from recorded utterances or to synthesize speech by assembling prerecorded phonemic segments. One reason for the difficulty lies in the fact that the perceptually discrete phonemes are typically combined, and in some cases encoded, into units of essentially syllabic dimensions. As a result, prerecorded elements must, in many cases, approximate syllables, and the synthesis of speech by this means will require a large inventory of recordings. By taking advantage of knowledge about the acoustic cues for speech perception, however, it is possible to write rules for synthesis in terms of phonemes (rather than syllables) and thus reduce considerably the number of separate rules or items needed. Indeed, one can reduce the number of rules still further by writing them at the level of subphonemic dimensions,viz., place and manner of articulation. Several complicating factors make it impossible to achieve an ideal minimum. First, rules or rule modifiers must be added to take care of certain prosodic and positional variations. Failure to do so not only affects naturalness, but also impairs intelligibility, even at the level of segmental phonemes. Second, it is necessary in a few special cases to have different rules for a single consonant phoneme (or a dimension of that phoneme) before different vowels. This reflects the occasionally complex relation between phoneme and articulation on the one hand and sound output on the other; presumably, this complication would not affect the rules of synthesis for an articulatory model.A system of rules for synthesis framed largely in terms of subphonemic dimensions is described with reference to an example. Words and sentences of rather high intelligibility have been synthesized by such rules.

ISSN:0001-4966    

DOI:10.1121/1.1907654

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The fundamental principle of language engineering—namely, that the probability of a correct message reception is critically dependent upon the size of the set of messages available for communications—was examined experimentally. Accuracy of message reception was found to be independent of the message‐source uncertainty, but critically dependent upon the response uncertainty—or more exactly, upon the size of the set of relevant response categories. Implications for a conceptual model of the listener's behavior are suggested.

ISSN:0001-4966    

DOI:10.1121/1.1907655

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The improvement in word intelligibility associated with successive presentations of a word in noise was examined with recorded and with independent samples of the speech and/or its background noise. The listener's criterion for termination of a trial was shown to be a crucial determinant of the gain of intelligibility with successive presentations. The improvement in intelligibility was greater for independent samples of speech and noise than for successive presentations of a single recorded sample. The observed improvement, however, was less than predicted for the ideal observer with perfect memory by the theory of signal detectability. Indexes of response discriminability and signal discriminability are briefly discussed.

ISSN:0001-4966    

DOI:10.1121/1.1907656

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The mechanism which gives rise to the intense vibrations of an acoustic air‐jet generator is investigated both experimentally and theoretically. The results indicate that the mechanism for establishing the vibrations in the generator consists of pressure instabilities in the nozzle air stream which act as the source of the forced oscillations of an air plug in the resonator cavity.

ISSN:0001-4966    

DOI:10.1121/1.1907657

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

A study is made of high frequency (10 mc/sec) barium titanate transducers radiating into water, with band width and efficiency being of principal concern. Optimum electrical damping alone is considered; however, it is demonstrated that the introduction of an intermediate14 wavelengththick composite mechanical element results in superior performance. Of the units constructed, the best exhibited a frequency band width (half‐power points) of 44% with 4‐db midband loss (equivalent insertion loss on a 2 transducer basis). Focusing radiators, as well as plane, were tested.

ISSN:0001-4966    

DOI:10.1121/1.1907658

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

Ultrasonic attenuation measurements in an aluminum single crystal near the superconducting transition temperature are described. These include both longitudinal and shear wave attenuations at frequencies of between 11 and 58 Mc/sec and at temperatures between 1.0 and 4.2°K, as well as attenuation as a function of magnetic field in the normal state. It is found that the attenuation of shear waves at the transition temperature shows a discontinuity of about 25% of the total attenuation, this fraction being relatively independent of frequency. The longitudinal wave attenuation shows a sharp but continuous drop at the transition temperature. It is shown that the electron mean free pathlcan be estimated from the magnetic field dependence of the attenuation and that the conditionkl<1 (k= 2π/λ, λ being the ultrasonic wavelength) holds for the measurements. The possible significance of the shear wave discontinuity is discussed.

ISSN:0001-4966    

DOI:10.1121/1.1907659

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

A one‐dimensional treatment of the propagation of a pressure pulse through a channel carrying a compressible flow is given. The method consists of summing the multiple linear reflections of increasing order, the “transmission” and “reflection” coefficients then being given in the form of power series whose terms depend only on the entry and exit Mach numbers of the mean flow. The series fails to converge under certain circumstances, but there is nothing corresponding to this in the equivalent results obtained from “before” and “after” steady‐state considerations. Both methods are shown to fail at a sonic throat, where it is suggested that the assumption of one‐dimensional perturbations is no longer tenable.

ISSN:0001-4966    

DOI:10.1121/1.1907660

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

摘要:

The acoustic radiation force of a plane wave impinging on a rigid sphere of diameter 10 cm and on a circular disk of diameter 7.4 cm has been measured in the wavelength interval 4 to 40 cm. The agreement with theory is satisfactory.

ISSN:0001-4966    

DOI:10.1121/1.1907661

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1907662

出版商:Acoustical Society of America    

年代:1959

数据来源: AIP