摘要:

Psychoacoustic studies have indicated that the pitch corresponding to the fundamental frequency of certain complex stimuli may be mediated through the temporal pattern of neural discharges. To evaluate this proposal, two populations of units from the cochlear nucleus were examined for their responses to modulated stimuli: (1) Those units with maximum sensitivity for sinusoidal stimuli of 800 Hz or less were presented with modulated stimuli having a low‐frequency fundamental, but with spectrum controlled to reduce the contribution of low‐frequency energy; (2) units with maximum sensitivity in higher‐frequency regions were studied using the stimulus frequency to which each was most sensitive and modulating it at low rates. The results suggests that units were not sensitive to the periodicity characteristics of a stimulus,per se, but that they also require certain spectral information. Once a unit is driven to respond , however, it is likely to reflect the periodicity of the stimulus in its discharge patterns.

ISSN:0001-4966    

DOI:10.1121/1.1911390

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

The masking effect of a broad‐band noise, a sinusoidal tone, or both may be represented in a simple three‐dimensional space. The space shows performance as function of (1) the level of the sinusoidal components relative to the noise, and (2) the relative energies in the signal plus sinusoidal masker waveform and the waveform of the sinusoidal masker alone. Results that appear complex in other representations appear straightforward in this space. For example, over wide ranges, neither frequency and duration of the signal nor the relative interaural phase of the signal and masking stimuli affects the shape of the space, but produces, at most, only a simple translation. Several theoretical descriptions of the space are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911391

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

An experiment is reported on the effects of different signal‐onset conditions, as a function of signal frequency, on the minimum audible angle obtained with human listeners in a free‐field localization situation. Transient binaural differences associated with signal onset were computed on the basis of: (1) the binaural distance difference; (2) the headshadow effect; and (3) the rise time of the signal. The results of the experiment indicate that signal onset may be treated as a short‐duration binaural intensity‐difference cue. The implications for a theoretical model of localization are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1911392

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Absolute and differential thresholds for a single temporal discontinuity, or “gap,” were obtained for auditory pulse trains as a function of: (1) the interpulse interval surrounding the gap region, and, (2) the magnitude of the reference gap. Under conditions implicating a spectral analysis, e.g., a large number of pulses at high pulse frequencies, the differential asynchrony threshold is extremely sensitive to the ratio of the reference gap to its surround. Under such conditions, the differential asynchrony threshold increases sharply as the gap/surround ratio changes by a factor of 2, but is relatively independent of still further changes in the gap/surround ratio. Under conditions implicating a temporal analysis, e.g., at low pulse frequencies, or an incomplete spectral analysis, e.g., a small number of pulses at high pulse frequencies, the differential asynchrony threshold is relatively insensitive to the gap/surround ratio.

ISSN:0001-4966    

DOI:10.1121/1.1911393

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Synthetic fundamental frequency contours were classified by Polish and American‐English listeners as indicating either statements or questions. Graphic analyses were applied to listeners' responses in order to isolate the most prominentF0cues that served to differentiate statements from questions. Comparisons between the response distributions for the two language groups revealed both common and language‐specific cues forF0contour identification.

ISSN:0001-4966    

DOI:10.1121/1.1911394

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

A digital speech analysis‐synthesis system based on a recently proposed approach to the deconvolution of speech is presented. The analyzer is based on a computation of the cepstrum considered as the inverse Fourier transform of the log magnitude of the Fourier transform. The transmitted parameters represent pitch and voiced unvoiced information and the low‐time portion of the cepstrum representing an approximation to the cepstrum of the vocal‐tract impulse response. In the synthesis, the low‐time cepstral information is transformed to an impulse response function, which is then convolved with a train of impulses during voiced portions or a noise waveform during unvoiced portions to reconstruct the speech. Since no phase information is retained in the analysis, phase must be regenerated during synthesis. Either a zero‐phase or minimum‐phase characteristic can be obtained by simple weighting of the cepstrum before transformation.

ISSN:0001-4966    

DOI:10.1121/1.1911395

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Respiratory volumes during phonation of a series of voiced and voiceless fricatives and plosives placed within a carrier phrase were measured in 20 normal adult subjects. The purpose was to (1) determine whether consonant type influences respiratory volume and (2) determine whether intraoral pressure differences among voiced‐voiceless consonants could be a reflection of volume differences during speech. The results indicate that voiceless consonants utilize substantially larger volumes of air than their voiced cognates. The data also suggest that consonant intraoral pressures may be influenced more by intraoral respiratory volumes than by energy losses caused by glottal resistance during voicing.

ISSN:0001-4966    

DOI:10.1121/1.1911396

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Thermal attenuations for dielectric crystals due to the Akheiser effect show characteristic patterns connected with crystal structure. For cubic crystals, the nonlinearity constantsD—which determine the coupling of acoustic waves with the thermal phonons—are all larger for the longitudinal waves than they are for the shear waves by ratios that vary from 5 to 17. On the other hand, for trigonal and hexagonal crystals, the constants are in the same order. It is the purpose of this paper to investigate whether these conclusions hold for metal crystals. For these crystals, there are three sources of square‐law attenuation for longitudinal waves and two for shear waves. These are the thermoelastic effect, the phonon viscosity (Akheiser effect), and the electron‐damping effect. Previous measurements for the cubic crystals lead, aluminum, and copper, made over a temperature range, are analyzed for these three components, and it is shown that the phonon viscosityDvalues vary from 5.3 to 17.5 for the ratio of longitudinal to shear values in agreement with the results for dielectric crystals. New measurements are presented for the hexagonal single crystal cadmium. It is shown that all dislocation motions, generated by the small strains used, lie in the direction of easy glide, i.e., in a plane perpendicular to thecaxis. The longitudinal wave along thecaxis and the three waves perpendicular tocall have only a square law attenuation. When the thermoelastic effect and the electronic damping effect are subtracted out, the nonlinearity constants have the same order of magnitude for both longitudinal and shear waves. Dislocation damping appears in the shear wave in thecdirection. The ratio of the number of dislocations to the damping constant is evaluated and is shown to be smaller than that for other pure crystals. This is consistent with phonon damping of dislocations on account of the large nonlinearity constantDfound for shear motion in the glide plane. When an attempt was made to measure this damping over a temperature range, it was found that a sudden increase in the attenuation occurs for shear waves controlled by thec44elastic constant.

ISSN:0001-4966    

DOI:10.1121/1.1911397

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

Sound velocity and absorption measurements have been made in pureH2Sat 300°K and inCO2/H2Smixtures at 300° and 500°K. The results of the measurements on pureH2Sindicate no observable relaxation taking place at frequency‐to‐pressure ratios less than 1200 kHz/atm. The measurements onCO2/H2Smixtures showed theCO2absorption peak to be shifted to higher frequency‐to‐pressure ratios by the addedH2Sat rates of 61.8 and 64.8 kHz per percentH2Sat 300° and 500°K, respectively. From this, the relaxation times for the bending vibration of aCO2molecule in 1 atm ofH2Sare calculated to be 3.16 × 10−8and 2.97 × 10−8sec at the two temperatures. These values are in order‐of‐magnitude agreement with values calculated on the assumption that theCO2vibrational energy is exchanged with the rotational energy of theH2Smolecule in the relaxation process.

ISSN:0001-4966    

DOI:10.1121/1.1911398

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP

摘要:

This paper describes the application of the geometrical theory of diffraction to the calculation of the far‐zone radiation pattern of a linear array mounted in a rigid rectangular box. Some theoretical patterns obtained with the method are presented and compared with experimental results.

ISSN:0001-4966    

DOI:10.1121/1.1911399

出版商:Acoustical Society of America    

年代:1969

数据来源: AIP