摘要:

The relative significance of spectral and temporal envelopes for the synthesis of orchestral wind‐instrument tones was evaluated by exchange of spectral and temporal envelopes among the wind instruments, by creation of artificial spectral envelopes, and by perturbation of the spectral envelopes. It was found that, for the oboe, clarinet, bassoon, tuba, and trumpet, where the spectral envelope is unique as regards the frequency of its maximum and the range in which the instrument is normally played, this envelope predominates in aural significance over the temporal envelope. Where the spectral envelope is not unique—as for the flute, trombone, and French horn the spectral envelope is equal or subordinate to the temporal one in aural significance. Interfamily confusions are fewer in those cases where the spectral envelope is of predominant importance: about 14% for the clarinet, oboe, bassoon, and tuba anti about 25% for the flute, trumpet, trombone, and French horn. The ratio between identification probabilities of synthetic and natural tones is 0.97 for the oboe, 0.90 for the clarinet, 0.86 for the French horn, 0.82 for the bassoon, 0.77 for the flute, 0.75 for the trumpet, 0.69 for the tuba, and 0.62 for the trombone.

ISSN:0001-4966    

DOI:10.1121/1.1910337

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Two experiments were performed to investigate the effects of transmission delay and access delay, respectively, on the efficiency with which speakers verbally encoded information for transmission in a two‐person communication task. Both experiments employed echo‐free four‐wire voice circuits in an attempt to isolate each delay effect and to avoid the delayed echo effect found in commercial circuits. In the first experiment, three values of pure roundtrip transmission delay were used: no delay, 0.6 sec, and 1.8 sec. Using 14 pairs of male subjects in each condition, it was found that, whereas 1.8 sec of transmission delay deleteriously affected the efficiency of communication, subjects performed as efficiently using the 0.6‐sec delay circuit as with no delay. In the second experiment, three values of access delay were used: no delay, 0.25 sec, and 1.8 sec. Ten pairs of male subjects and 10 pairs of female subjects were run in each condition. The effect of access delay was found to be different for the two sexes. Access delay of 1.8 sec had a greater effect on males than on females, whereas at 0.25‐sec delay female performance was impaired slightly and male performance not at all. With no delay, male and female performance did not differ. These results are supported by data based on subjects' responses to a postexperiment questionnaire. The findings are discussed in terms of their relevance to problems encountered in two‐way voice communication over long transmission paths.

ISSN:0001-4966    

DOI:10.1121/1.1910338

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The cepstrum, defined as the power spectrum of the logarithm of the power spectrum, has a strong peak corresponding to the pitch period of the voiced‐speech segment being analyzed. Cepstra were calculated on a digital computer and were automatically plotted on microfilm. Algorithms were developed heuristically for picking those peaks corresponding to voiced‐speech segments and the vocal pitch periods. This information was then used to derive the excitation for a computer‐simulated channel vocoder. The pitch quality of the vocoded speech was judged by experienced listeners in informal comparison tests to be indistinguishable from the original speech.

ISSN:0001-4966    

DOI:10.1121/1.1910339

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The essential features of the coarticulation properties of Swedish dental stops in vowel‐consonant‐vowel contexts can be described by the formulas(x; t) = v(x; l)+k (t)[c(x) − v(x; t)]wc(x), wherexrepresents the longitudinal distance between lips and glottis ands(x;t) denotes the shape of the vocal tract at some instant of time,t, during the vowel‐consonant vowel utterance. The vowel component,v(x;t) is a linear combination of the three “extreme” shapes of the vowels /i/, /a/, and /u/ with weights that vary as functions of time. The consonant is represented byc(x), an ideal target shape, andwc(x), a so‐called coarticulation function. A time varying factork(t) represents the degree of excursion of the consonantal gesture. Vocal tract shapes measured from x‐ray motion pictures of a set of Swedish vowel‐consonant vowel utterances compare well with shapes generated by the formula. This result is consistent with our earlier conclusions about coarticulation, viz., that the vowel and consonant gestures are largely independent at the level of neural instructions.

ISSN:0001-4966    

DOI:10.1121/1.1910340

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

An acoustic‐emission loading and detection system is described and the detection system's harmonic response to both longitudinal and flexural waves is evaluated. Photographs of acoustic‐emission response pulses are presented, and it is shown that the flexural waves are of considerable importance in describing the detection systems's response to the acoustic‐emission source pulse. An estimate indicates that the energy of the flexural part of one acoustic‐emission pulse is two orders of magnitude greater than the energy of the longitudinal part.

ISSN:0001-4966    

DOI:10.1121/1.1910341

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

Conduction electrons, owing to their inertia, should move relative to an accelerated metallic lattice as they would in a stationary conductor if subjected to an electric field equal to the mass/charge ratio of an electron times the acceleration of the lattice. Since a strain pulse produces a transient acceleration, it should be accompanied by an electron‐inertia field of this type. To demonstrate this effect, a torsional strain pulse was used to produce rotational acceleration of an insulated metal ring, and the electromagnetic signal, generated by the ring during acceleration, was detected by a pickup coil connected to an oscilloscope. The theory of a strain‐induced electron‐inertia effect is discussed, and calculations are carried out for comparison with measurements. Reasonable agreement between measurement and prediction serves to identify electron inertia as the cause of the signal.

ISSN:0001-4966    

DOI:10.1121/1.1910342

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

It is shown how the pulse‐echo method for determining sound velocities and acoustic attenuation can be applied to thin specimens by generating short stress pulses with thick transducers. The method is described in conjunction with its use in the observation of phase transformations in which both transit‐time data and attenuation measurements are used to determine the mechanism and kinetics of the transformation. Results are shown for the β → α a phase transformation in high‐purity plutonium.

ISSN:0001-4966    

DOI:10.1121/1.1910343

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

A method for using the well known modes of vibration for the infinite plate as elements of an expansion applicable to semi‐infinite plates is given. The method is employed to study the reflection of an infinite train of waves from the free edge of an elastic plate. The incident train of waves induces other, nonpropagating, modes. As has previously been discovered, a resonance may occur in such a mode that will increase the portion of the plate for which the evanescent modes affect the stress distribution. Above a critical frequency, a transfer of energy from one propagating mode to another occurs during the reflection. Generally, energy brought to a free edge by waves of one wavelength will depart in wave trains of several different wavelengths. The presence of a mode which, for a limited range of frequency, carries energy in a direction opposite to the motion of the waves is confirmed. Some observations are made about necessary restrictions in an extension of St. Venant's principle to dynamic loadings.

ISSN:0001-4966    

DOI:10.1121/1.1910344

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

This paper describes a vibration transfer standard designed to provide comparison calibrations of pickups with minimum degradation. Features of the design are the use of a ceramic housing of a stiff, light, lossy material; provision of a means for evaluating the quality of the motion by the use of three integral accelerometers oriented parallel to the nominal direction of motion; and design of the geometry to minimize differences in motion between the pickup being calibrated and the standard. The useful frequency range is 10–10 000 Hz.

ISSN:0001-4966    

DOI:10.1121/1.1910345

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP

摘要:

The dynamic response of a circular, elastic shell in plane strain, when given an impulsive radial load, is studied. Inextensional bending is assumed and approximate solutions are obtained for the behavior at the wavefronts and for some time after the wave has passed. The method of Friedlander as applied by Payton to shells is used to study the wave propagation for relatively long times, and the bending‐moment distribution is obtained.

ISSN:0001-4966    

DOI:10.1121/1.1910346

出版商:Acoustical Society of America    

年代:1967

数据来源: AIP