Relationships between Several Indices of Acoustic Reflex Function and Susceptibility to Temporary Threshold Shift Produced by Different Spacings of Impulsive Noise and by Continuous Noise

1968 ◽  
Vol 44 (1) ◽  
pp. 352-352
Author(s):  
John L. Fletcher ◽  
Ernest M. Weiler ◽  
Michel Loeb
Keyword(s):  
Impulsive Noise ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Acoustic Reflex ◽  
Continuous Noise

Acoustic-Reflex Dynamics for Pulsed Signals

1978 ◽  
Vol 21 (2) ◽  
pp. 295-308
Author(s):  
Terry L. Wiley ◽  
Raymond S. Karlovich
Keyword(s):  
Duty Cycle ◽  
Acoustic Impedance ◽  
Normal Hearing ◽  
Broadband Noise ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Acoustic Reflex ◽  
Stapedius Muscle ◽  
Duty Cycles

Contralateral acoustic-reflex measurements were taken for 10 normal-hearing subjects using a pulsed broadband noise as the reflex-activating signal. Acoustic impedance was measured at selected times during the on (response maximum) and off (response minimum) portions of the pulsed activator over a 2-min interval as a function of activator period and duty cycle. Major findings were that response maxima increased as a function of time for longer duty cycles and that response minima increased as a function of time for all duty cycles. It is hypothesized that these findings are attributable to the recovery characteristics of the stapedius muscle. An explanation of portions of the results from previous temporary threshold shift experiments on the basis of acoustic-reflex dynamics is proposed.

Spectral and Temporal Parameters of Contralateral Signals Altering Temporary Threshold Shift

1974 ◽  
Vol 17 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Raymond S. Karlovich ◽  
Terry L. Wiley
Keyword(s):  
Dynamic Properties ◽  
Broad Band ◽  
Normal Hearing ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Acoustic Reflex ◽  
Contralateral Stimulation ◽  
Band Noise ◽  
Resultant Data ◽  
Contralateral Ear

The test ear of each of nine normal-hearing subjects was exposed for three minutes to a 1000-Hz tone at 110 dB SPL. Either a 4000-Hz tone at 105 dB SPL or a broad-band noise at 100 dB SPL was presented to the contralateral ear during exposure. Four different temporal patterns were used for each contralateral signal: (1) continuous, (2) 18 seconds on/18 seconds off, (3) 1.8 seconds on/1.8 seconds off, and (4) 0.18 seconds on/0.18 seconds off. A control condition, consisting of the absence of contralateral stimulation, also was used. Pre- and postexposure thresholds for the test ear were tracked at a signal one-half octave above the exposure frequency. Resultant data indicated that reduction in temporary threshold shift was greatest for conditions involving rapidly pulsed (1.8 and 0.18 seconds on-off) contralateral signals. We hypothesized that these data were reflective of the dynamic properties of the acoustic reflex. Specifically, we posited that the acoustic reflex manifests less adaptation in response to rapid signal-repetition rates and relatively more adaptation to sustained or slowly pulsed signals.

Temporary Threshold Shift following 24-Hour Noise Exposure

1977 ◽  
Vol 86 (6) ◽  
pp. 821-826 ◽  
Author(s):  
William Melnick
Keyword(s):  
Noise Level ◽  
Noise Exposure ◽  
Sound Field ◽  
Threshold Shift ◽  
Exposure Level ◽  
Temporary Threshold Shift ◽  
Octave Band ◽  
Straight Line ◽  
Hearing Thresholds ◽  
Continuous Noise

Nine men were exposed to 24 hours of continuous noise in a sound field. The noise was an octave band centered at 4 kHz at levels 80 and 85 dB. Hearing thresholds were measured monaurally at 11 test frequencies ranging from 250 to 10000 Hz before, during, and after exposure. Temporary threshold shift (TTS) reached maximum levels at 8 to 12 hours of exposure. Maximum TTS occurred at 4 and 6 kHz. Mean asymptomtic threshold shifts (ATS) resulting from the 80 dB exposure level were 9.3 dB for 4 kHz and 7.2 dB for 6 kHz. For the 85 dB noise level, these threshold shifts were 17.8 dB and 14.6 dB respectively. The increase in ATS with increase of noise level for these two frequencies could be fitted with a straight line having a slope of 1.6.

Evaluating temporary threshold shift onset levels for impulsive noise in seals

2020 ◽  
Vol 148 (5) ◽  
pp. 2973-2986
Author(s):  
Jillian M. Sills ◽  
Brandi Ruscher ◽  
Ross Nichols ◽  
Brandon L. Southall ◽  
Colleen Reichmuth
Keyword(s):  
Impulsive Noise ◽  
Threshold Shift ◽  
Temporary Threshold Shift

The Acoustic Reflex and Temporary Threshold Shift: Temporal Characteristics

1977 ◽  
Vol 20 (3) ◽  
pp. 565-573 ◽  
Author(s):  
R. S. Karlovich ◽  
H. A. Osier ◽  
H. N. Gutnick ◽  
R. G. Ivey ◽  
K. Wolf ◽  
...  
Keyword(s):  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Acoustic Reflex ◽  
Temporal Characteristics

Asymptotic Threshold Shift (ATS) in Man from 24 Hour Exposure to Continuous Noise

1974 ◽  
Vol 83 (6) ◽  
pp. 820-828 ◽  
Author(s):  
William Melnick ◽  
Michael Maves
Keyword(s):  
Growth Pattern ◽  
Sound Field ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Octave Band ◽  
Time Intervals ◽  
Small Magnitude ◽  
Slow Development ◽  
Hearing Thresholds ◽  
Continuous Noise

Ten men were exposed to a 300–600 Hz band of noise at an octave-band-level of 90 dB in a sound field for a period of 24 hours. Hearing thresholds were measured in one ear at 11 test frequencies ranging from 125 to 8000 Hz prior to exposure and at selected time intervals during and after exposure. Temporary threshold shift (TTS) appeared to reach asymptotic levels by 12 hours of exposure. Maximum TTS was approximately 11 dB and occurred at 500, 750 and 1000 Hz. TTS was appreciable at 1500 Hz amounting to 7 dB and was less than 5 dB at other frequencies. The growth pattern of TTS was triphasic; slow development during the first two hours of exposure, a rapid increase from 2 to 8 hours, and then apparently reaching an asymptote by the twelfth hour. Recovery was prolonged for the relatively small magnitude of TTS, requiring 24 hours before most of the subjects returned to preexposure threshold levels. Asymptotic TTS (ATS) showed dependence on preexposure threshold hearing levels.

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