Temporary threshold shift (TTS) is generally believed to grow during noise exposure and recover afterwards in proportion to the logarithm of time. However, these logarithmic laws of TTS disagree with experimental observations made very early or very late in these processes. Better agreement with experiment is obtained if TTS is regarded as the sum of two components that vary exponentially with time. Published information on TTS was analyzed to determine the properties of these two components. Only one of the components is believed to be associated with permanent hearing loss resulting from noise exposure, and its simple electrical analog makes possible the construction of a TTS meter for appraising noise hazard. The analysis also revealed two other components of TTS that account for the “bounce” sometimes observed very early in the recovery process. Additional studies are needed to refine the theory and improve understanding of the auditory process.
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