摘要:

This research investigates the human observer's ability to judge differences in duration without the benefit of such cues as differences in energy and energy spectrum. Three observers compared two silent durations,TandT+ΔT, in a two‐alternative forced‐choice procedure. The value ofTranged from 0.63 to 640 msec. For eachT, seven values of ΔTwere chosen to cover the range of the psychometric function. The duration and amplitude of noise markers bounding the temporal gaps were varied across three experimental conditions. For silent durations less than 160 msec, the results showed that discrimination depended on the parameters of the marker. For each marker condition, the function relating the Weber fraction andTwas non‐monotonic, reaching a local minimum at about 2.5 msec and a local maximum at 10 msec. These results were used to evaluate current theories about the central processing of duration.

ISSN:0001-4966    

DOI:10.1121/1.1913139

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Binaural detection of a signal having 180° interaural phase difference (Sπ, 500 Hz, 125 msec) in broad‐band correlated noise having no interaural phase difference (N0, 46.1 dB/Hz) was investigated when broad‐band uncorrelated noise (NU, also 46.1 dB/Hz) temporally surrounded the 125‐msec observation interval. The N0 was switched from the NU either simultaneously with the onset of the observation interval, or 100, 300, or 500 msec before the onset of the observation interval. The N0 was switched back to NU at the end of the observation interval. Detection was also examined when the N0 was switched from NU at the start of the observation interval, but switched back to NU 100 or 300 msec following the end of the observation interval. When the temporal limits of the correlated noise coincided with the observation interval, the masking‐level difference (MLD) was less than that found when detecting in continuous correlated noise, even though the correlated noise had been switched from uncorrelated noise of the same level. Switching from uncorrelated noise to correlated noise before the observation interval,ordelaying the switch back to uncorrelated noise after the observation interval tended to restore the MLD.

ISSN:0001-4966    

DOI:10.1121/1.1913140

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Experiments that were designed to investigate the properties of a peculiar type of distortion that has been observed in the cochlea at high excitation intensities are described. The pairs consist of two components with frequencies that are equally spaced about one‐half the excitation frequency and that sum to the excitation frequency. Pairs centered on odd‐harmonics of one‐half the excitation frequency were also observed. The pairs exhibit a threshold of appearance, their frequencies can drift with time, and at excitation intensities well above threshold the pairs develop into noisy bands instead of remaining as discrete frequency components. Distortion pairs with similar properties were observed in five different species of the order Rodentia. An analogy between the behavior of the pairs with increasing excitation intensity and the development of turbulence in the boundary layer over a flat plate is discussed. The turbulence arises from an instability in the flow, and it is suggested that the cochlear distortion pairs develop from a similar instability in the cochlear flow.

ISSN:0001-4966    

DOI:10.1121/1.1913141

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

At least two explanations can be offered for the monaural phase effects reported in previous tone‐on‐tone masking experiments. The aural distortion approach leads to the prediction that changes in the phase angle between masker and maskee will cause sensitivity variations only at harmonic intervals. The two‐tone interaction approach suggests that phase effects should also be evident at nonintegral multiples of the masker. To test these predictions, six normal listeners traced their thresholds at 1500, 2000, and 2500 Hz in the presence of a 1000‐Hz masker at each of five intensities: 50–90 dB SPL in 10‐dB increments. Within each session, the phase was shifted in randomly ordered 60° steps through one complete period (of the maskee). When confusions due to a 500‐Hz difference tone are avoided by including a narrow‐band (270–510 Hz) masking noise, no phase effects are evident at 1500 and 2500 Hz. The thresholds for the 2000‐Hz maskee, however, show the usual phase dependencies. These findings are inconsistent with the two‐tone interaction explanation and support the interpretation that emphasizes nonlinear response of the auditory system and direct interference between the aural and acoustic harmonics. Furthermore, when estimates of the second aural harmonic are obtained, its magnitude appears to vary directly withf1intensity at the 2 dB/dB rate predicted from the power law description of amplitude distortion.

ISSN:0001-4966    

DOI:10.1121/1.1913142

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The effects of electrically biasing the cochlear partition on the summating potentials were investigated in guinea pigs. The DIF (DIF = SV − ST) and AVE (2 AVE = SV + ST) SP responses were observed under polarization as well as the cochlear microphonics. These responses were recorded and the cochlear partition was polarized in the first and third turns; a wide range of stimulus parameters was utilized. The negative DIF and positive AVE components exhibited similar qualitative effects of electrical biasing as the (pure tone) CM, but the amount of change induced in the former responses was typically three or more times greater than that seen in the CM. While the DIF+exhibited the opposite effects of polarization, compared to these responses, the results revealed an underlying relationship between the positive and negative DIF responses. As a rule, positive polarization currents caused the DIF responses to become less positive and more negative while the opposite was true for negative currents. No systematic level‐dependent effects of electrical biasing were observed in the behavior of the negative DIF or positive AVE or in the positive DIF, given the complexities of its input‐output function (without polarization). The results pertaining to the negative AVE component provided little basis for concrete conclusions concerning the effects of polarization on this component. The findings of this investigation reflect the involvement of electromechanical nonlinearities in the generation of the summating potentials.

ISSN:0001-4966    

DOI:10.1121/1.1913143

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The cochlear hair cell has a remarkably high sensitivity to the displacement of the basilar membrane of the inner ear. However, the detailed mechanism of the receptor process, especially for the high sensitivity, has not been fully established. The present article is concerned with the enhancement of the mechanosensitivity of the receptor hair cells of the lateral‐line organ of aquatic animals by the environmental potassium ions. The potassium ion on the receptor surface of the lateral‐line organ, the free standing neuromast, modified the receptor sensitivity to vibratory mechanostimuli. Studies on the free neuromast rather than on the canal neuromast may better contribute to the understanding of the excitation mechanism of the cochlear hair cell.

ISSN:0001-4966    

DOI:10.1121/1.1913144

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

The alternate binaural loudness balance technique was employed to investigate the effects of duty cycle (the percentage of time the sound is on) upon the perceived magnitude of 1000‐Hz pure‐tone signals. The reference signal was fixed in the right ear at 50‐dB sound‐pressure level (SPL). In the left ear, the comparison signal intensity was adjusted via a Békésy audiometer to yield equal interaural loudnesses. The loudness of interrupted signals increased as the signal duty cycle was increased. A low‐duty‐cycle comparison signal was consistently judged to be softer than an equally intense high‐duty‐cycle reference signal. Furthermore, a high‐duty‐cycle comparison signal was consistently judged louder than a low‐duty‐cycle reference signal of the same intensity. The greatest interaural loudness disparity was observed for the experimental conditions in which the interaural duty‐cycle difference (high duty cycle minus low duty cycle) was 80%. During a substantial number of trials, this relationship between duty cycle and loudness increased in magnitude throughout the 4‐min balancing period. Duty‐cycle‐loudness effects were enhanced when a 400‐msec silent interval separated alternating tones. The results of this study may be incorporated to assist in the explanation of the occurrence of the type‐V Békésy pattern in clinical audiology. In addition, they lead to questions concerning the interpretation of experiments in which interrupted signals are presented for loudness evaluation such as experiments on loudness adaptation.

ISSN:0001-4966    

DOI:10.1121/1.1913145

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

A method is presented for the insertion of microelectrodes into the scala media and fluid spaces of the organ of Corti without injury to the capillaries of the membranous labyrinth. Electrode placement is made under complete visual control and monitored on a closed‐circuit television system. Capillary blood flow and electrode position are constantly observed. With electrodes so placed, electrode current resulting from changes in oxygen concentration is measured as respiratory air to the animal is cut off and restored. Oxygen concentration in the tunnel of Corti decreases and returns to normal much more rapidly than does that of the endolymph of the scala media. These results furnish evidence that the spiral vessels of the basilar membrane (vas spirale) and spiral osseous lamina supply the oxygen to the fluids in the spaces of the organ of Corti.

ISSN:0001-4966    

DOI:10.1121/1.1913146

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

Detectability was measured as a function of signal duration for a dichotic condition in which there was only an interaural difference in level and for one in which there was only an interaural difference in time. For four subjects, performance improved as duration increased, and it did so in essentially the same way for the two dichotic conditions; however, one other subject was unusual in that he showed little improvement in performance as duration was increased when the sole interaural cue was a time difference. Masker and signal: the same band of noise, 50 Hz wide centered at 500 Hz. Method: single‐interval forced choice.

ISSN:0001-4966    

DOI:10.1121/1.1913147

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP

摘要:

This study attempted to investigate the mechanical response of skin‐tissue systems under conditions commonly employed in psychophysical investigations of the tactile system. The influence of these conditions on the specific mechanical impedance was determined and evidence was found suggesting that if one desires to avoid altering the mechanical characteristics, then the parameters to be controlled are the pressure exerted by the probe and the area of the probe. The presence of a surround also influenced the mechanical characteristics when the site of stimulation was the volar forearm, but not when it was the finger or the thenar eminence.

ISSN:0001-4966    

DOI:10.1121/1.1913148

出版商:Acoustical Society of America    

年代:1972

数据来源: AIP