On the Potential Deterioration in Hearing Due to Hearing Aid Usage

1981 ◽  
Vol 24 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Larry E. Humes ◽  
Fred H. Bess
Keyword(s):  
Hearing Aid ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Hearing Sensitivity

This manuscript examines the issue of potential decline in hearing sensitivity due to hearing aid usage through an analysis of data obtained from the temporary threshold shift (TTS) paradigm. Following a critique of the traditional measures of TTS, the concept of integrated TTS (ITTS) is reviewed and data on hearing-aid-induced ITTS are presented. In addition, a series of equations relating permanent threshold shift (PTS) to a recently developed measure of noise dose (Dn) is derived and predictions for hearing-aid-induced PTS are made. Recommended gain settings established to protect the hearing of a person wearing a hearing aid from further decline following various durations of hearing aid usage are also provided.

Prediction of Asymptotic Threshold Shift Caused by Hearing Aid Use

1994 ◽  
Vol 37 (6) ◽  
pp. 1450-1458 ◽  
Author(s):  
John H. Macrae
Keyword(s):  
Hearing Aids ◽  
Pure Tone ◽  
Hearing Aid ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
High Input ◽  
Hearing Aid Use ◽  
Sound Levels ◽  
Ambient Sound ◽  
Ambient Levels

This study used a well-verified mathematical model to predict asymptotic temporary threshold shift (ATS) caused by hearing aid use. The model determined the amounts of ATS to be expected if real ear insertion gains (REIGs) recommended by the current National Acoustic Laboratories (NAL) procedure are used. It also determined the consequences of use of excess REIG and of high input levels to hearing aids. If recommended REIGs are used and input levels are normal (average A-weighted input levels of about 61 dB SPL), ATS is unlikely to occur for clients who have typical audiograms with three-frequency average pure-tone thresholds (PTAs) less than 60 dB HL. For people with PTAs greater than 60 dB HL, small amounts of ATS can be expected to occur during hearing aid use, but these amounts of ATS are safe, that is, unlikely to be associated with permanent threshold shift (PTS) for individuals with all PTAs except those greater than about 100 dB HL. If REIGs are 15 dB greater than those recommended, the amounts of ATS will be unsafe for people with PTAs greater than about 80 dB HL. It appears unwise for clients who have this degree of hearing loss to use excess REIG. The use of excess REIG in high ambient levels of sound (average A-weighted input levels of about 75 dB SPL) is likely to cause PTS for hearing aid users with PTAs of about 50 dB HL or greater. Clients who prefer to use excess REIG should therefore avoid high ambient sound levels. The amount of amplification required for people with PTAs greater than about 100 dB HL is likely to cause PTS and is therefore inherently unsafe.

Temporary Threshold Shift Caused by Hearing Aid Use

1993 ◽  
Vol 36 (2) ◽  
pp. 365-372 ◽  
Author(s):  
John H. Macrae
Keyword(s):  
Hearing Aids ◽  
Noise Exposure ◽  
Hearing Aid ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Noise Levels ◽  
Hearing Aid Use ◽  
Wide Range ◽  
The Mean ◽  
Modified Power Law

Temporary threshold shift (TTS) over a wide range of frequencies was found after 4 hours of hearing aid use by a 15-year-old student with severe sensorineural hearing loss who was using real-ear insertion gains 10 to 20 dB greater than those recommended by the current National Acoustic Laboratories (NAL) procedure for selecting the gain and frequency response of hearing aids. Measurements were made of her noise exposure during hearing aid use with a noise dosimeter. The real-ear insertion response and input-output function of her hearing aid were measured with a real-ear gain analyzer and were used to calculate in-ear noise levels from the noise levels measured by the dosimeter. The amount of TTS could be predicted from the in-ear noise levels and the student’s hearing levels (HLs) by means of a mathematical model consisting of the Modified Power Law (MPL) of Humes and Jesteadt (1991) combined with equations for predicting TTS in listeners with normal hearing published by Mills, Gilbert, and Adkins (1979). The mean of the instantaneous A-weighted in-ear noise levels proved to be the appropriate equivalent continuous level (ECL) for use in the predictions. The MPL was also used to determine safety limits for TTS due to hearing aid use. The observed TTS exceeded the safety limits at all frequencies up to and including 2000 Hz. It was therefore considered desirable for the girl to use less gain at frequencies from 500 to 1500 Hz.

An Investigation of Temporary Threshold Shift Caused by Hearing Aid Use

1994 ◽  
Vol 37 (1) ◽  
pp. 227-237 ◽  
Author(s):  
John H. Macrae
Keyword(s):  
Mathematical Model ◽  
Hearing Loss ◽  
Hearing Aid ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Hearing Aid Use ◽  
Gain Reduction ◽  
The Mathematical Model ◽  
Békésy Audiometry ◽  
Modified Power Law

Temporary threshold shift (TTS) caused by hearing aid use was measured by Bekesy audiometry in a group of individuals with severe sensorineural hearing loss. The accuracy with which a mathematical model consisting of the Modified Power Law (MPL) (Humes & Jesteadt, 1991) combined with equations for predicting TTS in normal listeners (Mills, Gilbert, & Adkins, 1979) could predict the TTS was evaluated. When the exponent of the MPL was set to 0.15, the predicted TTS was significantly greater than the observed TTS at two out of six frequencies. When the exponent was increased to 0.20, there were no significant differences between the predictions and the observations. With this value of the exponent, the mathematical model was able to predict the observed TTS as accurately as it could be measured. The MPL was used to derive safety limits for TTS, and gain reduction was recommended as the best method of reducing TTS to the safety limits.

Decay of Temporary Threshold Shift in Noise

1973 ◽  
Vol 16 (2) ◽  
pp. 267-270 ◽  
Author(s):  
John H. Mills ◽  
Seija A. Talo ◽  
Gloria S. Gordon
Keyword(s):  
Sound Field ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Octave Band ◽  
Band Noise ◽  
Lower Asymptote

Groups of monaural chinchillas trained in behavioral audiometry were exposed in a diffuse sound field to an octave-band noise centered at 4.0 k Hz. The growth of temporary threshold shift (TTS) at 5.7 k Hz from zero to an asymptote (TTS ∞ ) required about 24 hours, and the growth of TTS at 5.7 k Hz from an asymptote to a higher asymptote, about 12–24 hours. TTS ∞ can be described by the equation TTS ∞ = 1.6(SPL-A) where A = 47. These results are consistent with those previously reported in this journal by Carder and Miller and Mills and Talo. Whereas the decay of TTS ∞ to zero required about three days, the decay of TTS ∞ to a lower TTS ∞ required about three to seven days. The decay of TTS ∞ in noise, therefore, appears to require slightly more time than the decay of TTS ∞ in the quiet. However, for a given level of noise, the magnitude of TTS ∞ is the same regardless of whether the TTS asymptote is approached from zero, from a lower asymptote, or from a higher asymptote.

Damage Risk: An Evaluation of the Effects of Exposure to 85 versus 90 dBA of Noise

1976 ◽  
Vol 19 (2) ◽  
pp. 216-224 ◽  
Author(s):  
James T. Yates ◽  
Jerry D. Ramsey ◽  
Jay W. Holland
Keyword(s):  
White Noise ◽  
Statistical Difference ◽  
Noise Exposure ◽  
Threshold Shift ◽  
Temporary Threshold Shift ◽  
Noise Levels ◽  
Potential Damage ◽  
Full Day ◽  
Damage Risk

The purpose of this study was to compare the damage risk of 85 and 90 dBA of white noise for equivalent full-day exposures. The damage risk of the two noise levels was determined by comparing the temporary threshold shift (TTS) of 12 subjects exposed to either 85 or 90 dBA of white noise for equivalent half- and full-day exposures. TTS was determined by comparing the pre- and postexposure binaural audiograms of each subject at 1, 2, 3, 4, 6, and 8 kHz. It was concluded that the potential damage risk, that is, hazardous effect, of 90 dBA is greater than 85 dBA of noise for equivalent full-day exposures. The statistical difference between the overall effects of equivalent exposures to 85 dBA as compared to 90 dBA of noise could not be traced to any one frequency. The damage risk of a full-day exposure to 85 dBA is equivalent to that of a half-day exposure to 90 dBA of noise. Within the limits of this study, TTS t was as effective as TTS 2 for estimating the damage risk of noise exposure.

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.

Onset, growth, and recovery of in-air temporary threshold shift in a California sea lion (Zalophus californianus)

2007 ◽  
Vol 122 (5) ◽  
pp. 2916 ◽  
Author(s):  
David Kastak ◽  
Colleen Reichmuth ◽  
Marla M. Holt ◽  
Jason Mulsow ◽  
Brandon L. Southall ◽  
...  
Keyword(s):  
Threshold Shift ◽  
Zalophus Californianus ◽  
Temporary Threshold Shift ◽  
Sea Lion ◽  
California Sea Lion
Sign in / Sign up

Export Citation Format

Share Document