摘要:

The accuracy with which subjects could assign an azimuth position to a sound coming to them over earphones was studied. The subjects did about as well initially as Stevens and Newman's subjects did with an external source, and they showed a small amount of improvement with practice.

ISSN:0001-4966    

DOI:10.1121/1.1908697

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

Masked audiograms were studied as a function of the bandwidth, level, and frequency of a masking noise. In a reverse procedure, audiograms were determined when a movable, narrow, and approximately rectangular band of noise was used as signal in the presence of one or more masking tones. In both cases changes in the masked audiograms as a function of bandwidth made it possible to measure critical bandwidth. When masked audiograms were studied as a function of level, discontinuous changes in their height and shape occurred when the masking stimulus reached a certain “transition” level. If masking noises of subcritical or critical width were used, the growth of masking with level contained a discontinuity at a level of the masking stimulus equal to about 50 db SL. An abrupt change in the shape of the masked audiograms occurred at the same level. The change of shape when apure tonewas the masking stimulus consisted in the appearance of a “notch” one critical bandwidth above the frequency of the masking tone. Findings associated with the bandwidth parameter suggest interpretations of the critical band and of masking. The changes occurring at the transition level may indicate the threshold of the inner haircells.

ISSN:0001-4966    

DOI:10.1121/1.1908699

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

The loudness of four‐tone complexes centered at 250, 2000, and 4000 cps was measured as a function of the over‐all spacing, ΔF, of the components, both in the quiet and against various levels of a uniform masking noise. When the masking noise was held at a constant level, the loudness of the complex increased more with ΔFat moderate sensation levels—between about 30 and 60 db—than at either higher or lower levels. Near the masked as well as the absolute threshold, the loudnessdecreasedas ΔFwas increased beyond the critical bandwidth. Only when ΔFwas less than a critical band, was loudness independent of ΔFand was the amount of loudness summation invariant with level. These results support the hypothesis that the amount of loudness summation depends upon the slope of the loudness functions for the individual critical bands that form the complex.

ISSN:0001-4966    

DOI:10.1121/1.1908701

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

A 1‐hr exposure to a high‐frequency noise (2400–4800 cps at 100‐db SPL) was (a) preceded or (b) followed by a 1‐hr exposure to a low‐frequency noise (600–1200 cps at 110‐db SPL). Although both noises produced considerable temporary threshold shifts at frequencies just above the corresponding noise frequency, neither had any effect on the growth or recovery of shifts produced by the other. It is concluded that the course of the fatigue process at one area of the basilar membrane is relatively independent of conditions existing at other areas.

ISSN:0001-4966    

DOI:10.1121/1.1908703

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

Microphones can be calibrated by a primary technique in a diffuse sound field. The formula for the diffuse‐field voltage response is derived from the well‐known relationship for a reciprocal transducer in free space. It is shown that the reciprocity parameter for a diffuse‐sound field follows from that for free space by replacing the distance by the “diffuse‐field distance” of a point source. This distance depends only on the total absorption in the reverberation room. The experimental procedure is described in some detail and the results of the diffuse‐field calibration of a Western Electric 640 AA condenser microphone are presented.

ISSN:0001-4966    

DOI:10.1121/1.1908705

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

Four correlation systems are studied which make use of two pressure‐gradient receivers having first‐order cosine directional characteristics. The systems differ in the methods of steering both the receivers and the receiver baseline. The steering may be accomplished by rotation or by the insertion of appropriate time delays. The mean, variance, and output signal‐noise ratio are computed for each system when a distant localized signal source is present in both circular and spherical noise fields. In addition, the directive properties of the mean outputs are examined. For a signal with rectangular power spectrum, the main lobe widths of the mean outputs are found, the behavior of the means in the neighborhood of source direction is examined, and an investigation is made of the mean output level for steering directions removed from source direction.

ISSN:0001-4966    

DOI:10.1121/1.1908707

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

The methods of transform calculus are used to solve several problems in which the transient response of a piezoelectric transducer is of interest. The electrical signal produced by a step function of force is derived, both for open‐circuit and resistive loading at the electrical terminals, and the mechanical signal produced by a voltage step is also discussed. The analyses are performed for both the plate transducer in compressional thickness vibration and the bar in compressional length vibration, and the important differences between the two transducers are discussed. The analyses commence with the fundamental piezoelectric equations, and solutions are found which represent successive time‐delayed reflections of the mechanical transient between the end faces of the transducer. The results are also discussed with reference to the exact transmission‐line electrical equivalent circuits of the transducers, whose development is outlined briefly. Simple equivalent circuits which do not involve lines are described; these make it possible to determine many features of the transient without recourse to the full theoretical analysis.

ISSN:0001-4966    

DOI:10.1121/1.1908709

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1908711

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

摘要:

The hypersonic resonance of X cut quartz crystals 0.1 mm thick has been observed at room temperature. Six to twelve odd harmonics in the region 2950 3600 Mc have been excited in several crystals. Hypersonic radiation into water was detected.

ISSN:0001-4966    

DOI:10.1121/1.1908713

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.1908717

出版商:Acoustical Society of America    

年代:1961

数据来源: AIP