摘要:

The problem of psychophysiological acoustics is to determine the characteristics of auditory sensation in terms of the physical dimensions of the stimulus and the relation of physiological phenomena (in animals) to the same stimuli, and by comparison to infer the relation of the psychological function to the physiological. Four such correlations have been examined. (1) Data previously reported show a fairly good correspondence of the threshold function of electric response and the psychological thresholds. (2) Pitch perception depends upon selective resonance of different portions of the basilar membrane, although an intense tone activates a large area. The positions of maximal sensitivity were determined by the effect of localized lesions of the cochlea upon the threshold for electric response. The resulting map was compared with the map derived from the integration of Shower and Biddulph's data on pitch discrimination. The correspondence is very close (Fig. 1). (3) The equal loudness contours of Fletcher and Munson were compared with the corresponding contours of intensity required to produce equal electric responses from the cochlea. The correspondence is satisfactory. (4) The loudness function of Churcher was compared with the relation between the intensity of a 1000‐cycle tone and the magnitude of the electric response of the cochlea. The functions are similar as a first approximation, except at high intensities. The deviations are partly random, partly systematic. Theoretical explanations of the deviations are suggested. The size of the electric response of the auditory nerve, representing the total number of active fibers, also corresponds approximately to the loudness function. The loudness function does not correspond to the function obtained by integration of the difference limens for loudness (data of Riesz). A DL at high intensity involves the addition of more loudness and therefore the activation of more nerve fibers than a DL at low intensity. As a first approximation, the size of a DL in sones (units of loudness) is expressed byDL = KN1.2, whereNis the number of DL's above threshold.

ISSN:0001-4966    

DOI:10.1121/1.1915845

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

摘要:

The changes in pitch which result from changes in the loudness of low frequency tones were investigated for several frequencies between 75 and 1000 c.p.s. with a crew of 9 observers. The loudness levels covered the range 20 to 120, and both telephone receivers and a loudspeaker were used as sound sources. Fletcher's pitch standard, a pure tone of loudness level 40, was employed. All consistent judgments gave pitch shifts downward with increasing loudness, but large differences between individuals were found. Two observers perceived no shifts at any frequency or loudness while three others experienced changes greater than 35 percent at the highest intensity. Appreciable changes with time in individual judgments were found. There appeared insignificant difference between data obtained with telephone receivers or with the loudspeaker. A set of contours of equal loudness level, plotted on coordinates frequency and pitch change in percent, is given. These curves show a pitch change small at 1000 cycles, increasing to maximum at a low frequency and decreasing for still lower frequencies. The frequency of greatest shift increased from about 100 cycles at small loudness to about 200 at loudness level 120. The Appendix describes automatic test equipment that greatly simplified the testing routine and improved its accuracy.

ISSN:0001-4966    

DOI:10.1121/1.1915846

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915847

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915848

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915849

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915850

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

摘要:

The conventional method of timing sound decay to an adjustable threshold is made automatic by a system of relays which control the following sequence: When a predetermined sound level is attained in the chamber the source is turned off and an electric timer is started: when the sound level falls to the adjustable threshold the timer is stopped and the source is turned on again. This recurrent cycle is stopped after ten repetitions and the average time for a single decay may be read directly from the timer. The apparatus is entirely a.c.‐operated and 80 db of decay can be recorded in the middle audiofrequency range. It is found that a low‐pass electric wave filter can be used to eliminate the rapid fluctuations in the rectified output of the microphone amplifier without altering the recorded decay rate. This artifice, in conjunction with the warble tone, is capable of reducing the deviations from smoothness in the decay curves to a value comparable with the random timing error without resorting to rotating vanes in the sound chamber. A statistical analysis of the residual timing errors is given.

ISSN:0001-4966    

DOI:10.1121/1.1915851

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

摘要:

This paper considers theoretically the propagation of compressional and torsional waves in solid rods having membranes as side branches. An infinite cylindrical rod is loaded at equal intervals with flexible circular membranes attached at their outer edges to the inside of a circular cylinder (see Fig. 1). The assumption that longitudinal waves in the rod set up symmetrical transverse waves in the membranes leads to the conclusion that the structure is ahigh‐passcompressional wave filter. The limiting case of an infinitely rigid membrane is also investigated. There is next considered the case of torsional waves in the rod giving rise to radial torsional waves in the attached membranes which now may be treated either as flexible or rigid diaphragms. When the latter are rigidly clamped at their outer edges, the structure is found to be ahigh‐passtorsional wave filter. When the diaphragms are free at the outer edges, alow‐passfilter results. The transmission characteristics are given for each case along with numerical illustrations.

ISSN:0001-4966    

DOI:10.1121/1.1915852

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

摘要:

A new type of loudspeaker is described in which a single mechanism is coupled to two horns: a straight axis high frequency horn and a folded low frequency horn. A theoretical analysis of the combined system is given and experimental data are shown which indicate smooth uniform response from 50 to 9000 cycles, and an efficiency of the order of 50 percent over a large portion of this range.

ISSN:0001-4966    

DOI:10.1121/1.1915853

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1915854

出版商:Acoustical Society of America    

年代:1936

数据来源: AIP