摘要:

The loudness of complex sounds composed of three or four pure tones was measured as a function of the over‐all spacing ΔFbetween the lowest and highest components. The measured relation between loudness and ΔFwas compared to calculations from Zwicker's model of loudness summation. In eight ears with a conductive impairment, loudness summated normally and as predicted by the model; loudness remained approximately constant as a function of ΔFnear threshold and increased with ΔFbeyond the critical band at higher sensation levels. In eight ears with a cochlear impairment, loudness did not change with ΔFat any tested sensation level. This invariance of loudness was not predicted by tire model nor was it found in six normal ears tested in the presence of a 90‐dB uniform masking noise intended to simulate the cochlear impairment. Under masking, loudness summated as predicted. The unexpected results in cochlear pathology were ascribed, tentatively, to a possible widening of the critical band.

ISSN:0001-4966    

DOI:10.1121/1.1910066

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The residue pitch of an amplitude‐modulated carrier wave with fixed carrier frequencydecreasesfor small increases modulation frequency. This surprising experimental finding can be accounted for by considering the effect of phase modulation, synchronous and antiphasic with the amplitude modulation, on the temporal fine structure of the signal or its spectrum. Some conversion of amplitude modulation into phase modulation is known to occur in the mechanical response of the basilar membrane. However, for phase modulation to account fully for the pitch matches reported in the literature, additional amplitude‐to phase conversion must occur either in the mechanical‐to‐neural transduction or in the neural processing.

ISSN:0001-4966    

DOI:10.1121/1.1910067

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Part III: A finite‐difference method [P. Lloyd and M. Redwood, J. Acoust. Soc. Am.39, 346–361 (1966)] has been used to determine the resonant frequencies and vibration patterns of the first six contour modes of thin rectangular plates ofY‐cut quartz. Predicted resonant frequencies are compared with experimental results for plates of various proportions; in most cases, the difference is less than 1%, even though relatively coarse grids are used in the finite‐difference representation.

ISSN:0001-4966    

DOI:10.1121/1.1910068

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

A general analysis is presented of the systematic errors in phase‐detection and amplitude‐detection methods for establishing the velocity of sound propagated through gases confined in tubes.

ISSN:0001-4966    

DOI:10.1121/1.1910069

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

The passive resonance frequencies of the flute were measured with high precision and compared with the frequencies obtained by blowing. The differences, which vary from +20 to −25 cents over the scale, are wholly accounted for by air temperature and composition and by variation of coverage of the mouth hole. No frequency pulling due to the blowing mechanism was observed. Measurements of frequency and radiated power using an artificial blowing mechanism provide an explanation for the variations in lip configuration observed in photographs. The tapered head joint provides a partial compensation for lip‐coverage variation, but irregularities in the resonant column give marked departures from calculated frequencies based on a smooth tube.

ISSN:0001-4966    

DOI:10.1121/1.1910070

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Subjects selected from airport neighborhoods judged the acceptability of noise produced by actual aircraft flyovers and by recorded flyover signals on both a relative and absolute (category) basis. Judgments were compared with the maximum perceived‐noise level occurring during the flyovers. For a given perceived‐noise level, little difference between ratings of takeoff and approach noise or live and recorded noise signals was observed. In the relative‐judgment tests, a larger change in perceived‐noise levels (16 PNdB) was required for a doubling, or halving, of the acceptability rating than the 10 PNdB originally assumed in developing the perceived‐noise‐level scale. In making category judgments of noise acceptability, a distinct shift between outdoor and indoor judgments occurred. Comparison with previous judgments of aircraft noise, employing different category scales, suggests relatively good agreement as to the noise levels at which a significant degree of dissatisfaction with the noise environment is expressed.

ISSN:0001-4966    

DOI:10.1121/1.1910026

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Measurements of formant frequencies throughout the vocalic portions of a number of phonemically symmetric consonant‐vowel‐consonant utterances have been performed using spectrum‐matching techniques implemented on a digital computer. The contours representing the first two formants as a function of time are described in terms of several parameters, including initial and final frequencies, midpoint frequencies, durations, and measures of curvature. The data illustrate the manner in which each of these parameters is influenced by the features of the vowel and by place of articulation of the adjacent consonants. The results provide evidence that diffuse tense vowels in English are characterized by diphthongal asymmetric articulatory motions, whereas nondiffuse vowels are not, and that the influence of the consonantal environment on the articulation of the vowel is greater for lax vowels than for tense vowels. Some general statements are made concerning the extent to which contiguous vowels and consonants influence each other's production.

ISSN:0001-4966    

DOI:10.1121/1.1910027

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

A technique was developed for measuring the scattering of ultrasonic waves (25–65 kc/sec) from turbulence. The transmitter and receiver were of the solid‐dielectric, condenser type. The scattered signal was separated from the direct and reflected signals by means of pulses, and was measured at angles from 21.5° to 165°. Readings of the root mean square of the scattered wave were obtained, which were 10−6times the incident signal.

ISSN:0001-4966    

DOI:10.1121/1.1910029

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Ultrasonic‐pulse techniques are extended to very thin samples in the forms of films, foils, thin plates, whiskers, fibers, and fine wires. Details of the experimental techniques are described. Separate sample and transducer supports are used with independent micrometer screw adjustments to bring sample and transducers into alignment and nondestructive contact. The sample behaves like an elastic waveguide that propagates in the lowest‐order modes. Major emphasis is on the lowest compressional and horizontal shear modes in isotropic planar samples and lowest compressional and torsional modes in isotropic cylindrical samples. Propagation in the 10 Mc/sec region was achieved through planar samples ranging down to 1000 Å, in thickness and through cylindrical samples ranging down to a few microns in diameter. The thinnest samples require the use of buffer plates. Representative measurements of velocity and elastic constant are presented for metal, semiconducting, and insulating materials. Applications and limitations of the described techniques are discussed.

ISSN:0001-4966    

DOI:10.1121/1.1910030

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP

摘要:

Measurements have been made of the absorption of sound in air at13‐octave frequency intervals from 2000 to 12 500 Hz, as a function of humidity, at six temperatures in the range from −0.5° to 25.1°C at normal atmospheric pressure. The results of the new study are presented and compared with those of past investigations. Then a “best fit” is obtained to existing data. The resulting information is presented in both tabular and graphical form, useful for the solutions to problems of the calculation of attenuation of sound propagated in the atmosphere and the computation of the effects of air absorption in problems of room acoustics. These results have been extrapolated downward in frequency to 125 Hz and extrapolated to cover the temperature range from −10° to 30°C at normal atmospheric pressure.

ISSN:0001-4966    

DOI:10.1121/1.1910031

出版商:Acoustical Society of America    

年代:1966

数据来源: AIP