摘要:

The normal range of auditory sensitivity for pure‐tone signals (8000 to 18 000 Hz) has been well bracketed in laboratory studies, generally with experienced listeners. This study reports results obtained during a field survey of high‐frequency hearing conducted with 237 subjects at the 1968 Denver ASHA Convention. These results agree quite closely with data from the laboratory studies. The purposes of this study are threefold: (1) to report high‐frequency field survey audiometric thresholds as a function of age and sex; (2) to review and compare results of all previous reports of high‐frequency hearing threshold studies, with particular attention to differences in calibration techniques; and (3) to recommend the Zislis and Fletcher [J. Aud. Res.6, 189–198 (1966)] threshold results obtained from sixth through 12th grade girls, with smoothing and minor modifications at 16 and 18 kHz, as the best representation of the “most sensitive hearing” for frequencies from 8000 to 18 000 Hz. It is recommended that these values be used as an interim standard until such time as official standard values are promulgated.

ISSN:0001-4966    

DOI:10.1121/1.1913149

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Auditory thresholds were determined in the goldfish (Carassius auratus) for sound pulses with duty cycles from 1%–90% of 100‐ and 1000‐msec periods. Thresholds were also determined for pulses from 10 to 500 msec in duration with at least 490 msec between pulses. Results indicate that there are no differences in threshold between short pulses and continuous tones and that thresholds are the same whether there is a long or short signal off‐time between pulses. It is concluded that temporal summation does not occur in the goldfish and that enhanced sensitivity for long sounds, found in mammals, is unnecessary for fish since most fish sounds consist of short pulses. It is suggested that temporal summation most probably occurs in higher auditory centers in the brain of mammals and the lack of these centers is the reason for no temporal summation in goldfish.

ISSN:0001-4966    

DOI:10.1121/1.1913150

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

This paper describes research on combination tones of the typef1 − k (f2 − f1. Such tones are audible during stimulation by the two frequency componentsf1andf2, withf1

ISSN:0001-4966    

DOI:10.1121/1.1913151

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Combination tones corresponding tof1 − k (f2 − f1), withka small positive integer, are often audible during stimulation by the two frequency componentsf1andf2(f1

ISSN:0001-4966    

DOI:10.1121/1.1913152

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Twelve highly trained listeners detected tonal signals in the absence of external masking noise. The signals were 150 msec long and ranged from 125 to 4000 Hz. Fitted psychometric functions were steeper at high than at low frequencies requiring between 3‐ and 8‐dB increase in signal level to raise performance from 60% to 95% correct. The signal levels that yield 76% correct detection in a two‐alternative, forced‐choice psychophysical procedure were in good agreement with the International Standards Organization's recommended values of audiometric zero. The results are consistent with a limitation imposed on auditory sensitivity by a “system noise” which is composed of the noise in the ear canal at low frequencies, and a low‐level (−11 dB SPL) component of unspecified origin at medium and high frequencies. No qualitative differences were observed between detection without external masking noise and previous data on the detection of tones masked by noise.

ISSN:0001-4966    

DOI:10.1121/1.1913153

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A quantitative psychophysiological theory of central masking is developed and partially validated by means of psychophysiological comparisons. The theory assumes constant signal‐to‐noise ratio in the physiological domain for constant signal detectability, partial linear summation of dichotic inputs, and a direct proportionality between driven neural activity and sound intensity at near‐threshold intensities. All assumptions are based on psychophysical and physiological evidence independent of central masking. The theory is shown to predict accurately single‐unit characteristics of the auditory nerve and of primary‐like populations in the cochlear nuclei and the superior olive. Validating comparisons between calculated and empirical results are made in time, frequency, and intensity domains, for steady‐state and transient stimuli.

ISSN:0001-4966    

DOI:10.1121/1.1913154

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The behavioral responses of goldfish to a variety of amplitude‐modulated (AM) acoustic signals were studied using a stimulus generalization paradigm in combination with a classical conditioning method. Measurements were thus allowed of the equivalence among various complex and simple signals in controlling the conditioned respiration response. The goldfish's conditioned response to AM signals were found to be controlled by carrier frequency, modulation depth, and to a lesser extent, by modulation frequency in the 40‐Hz range. On the other hand, pure‐tone frequency exerted minimal behavioral control for subjects conditioned to AM signals. Subjects conditioned to a 40‐Hz pure tone tended to generalize maximally to an AM signal having a 40‐Hz modulation rate. The results indicate the degree to which the goldfish can use much of the information present in complex periodic acoustic signals and suggest the existence of periodicity pitch in fish.

ISSN:0001-4966    

DOI:10.1121/1.1913155

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The first part of this paper reports an experimental investigation of some parameters that control the occurrence of biologically effective cavitation‐type phenomena in the frequency region 0.25 4 MHz. The experimental criterion by which “cavitation” is recognized here is the simultaneous occurrence of degradation of DNA in aqueous solution, liberation of freeI2from KI solution, and generation of half‐order subharmonic. The intensity threshold for cavitation rises with frequency from 0.14 to 17.5 W cm−2(spatial peak) in the above frequency range. Pulse duration and duty factor are also found to be determining parameters, with cavitation activity reducing to zero when values of both parameters are sufficiently low. A strong positive correlation between ambient pressure and intensity threshold has also been determined. On the basis of observations of the levels of scattered half‐order subharmonic signals from various media, no evidence could be found for cavitation activity in sonicated mammalian tissues, although such activity could be detected in a wide range of liquids. The second part of the paper consists of a review, conducted in the light of the above results, of published experimental data relating to the existence and values of exposure thresholds for possible nonthermal, noncavitational mechanisms of action of ultrasound in living cells and tissues.

ISSN:0001-4966    

DOI:10.1121/1.1913156

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

In most ultrasonic diagnostic methods so far suggested, the output is in the form of a two‐dimensional image, and a serial set of cross sections is used to give three‐dimensional information about the part examined. The paper demonstrates the practicability of forming a section at any arbitrary angle through the three‐dimensional information using a digital computer. In addition, information from two mutually perpendicular sets of planes can be consolidated into a single series of echograms, thus overcoming to some extent the loss of information due to specular reflection. While this technique does not appear to be practical for routine diagnosis with the present generation of pulse‐echo machines, it would be simply incorporated in a computer‐based device using acoustical holography, Bragg imagery, or a transducer array technique for data acquisition.

ISSN:0001-4966    

DOI:10.1121/1.1913157

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Mouse Ehrlich ascites carcinoma cells and the amoebaHartmanella castellaniiwere subjected to an acoustic microstreaming field generated around a partially submerged transversely oscillating wire. The various forces responsible for the intracellular “consistency” (i.e., the viscoelastic tendency to resist mechanical deformation) of ascites cells are so strong that the organelles remain attached to each other after the plasma membrane has been torn off, whereas the cell contents of the amoebae are easily dispersed once the plasma membrane is ruptured. Present evidence suggests that the high internal consistency of ascites cells prevents any form of intracellular streaming, whereas the low internal consistency of amoebae might allow artifically induced streaming within the intact cell.

ISSN:0001-4966    

DOI:10.1121/1.1913158

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP