Temporal integration of acoustic energy.

Perception of sound shows an increase in loudness related to the duration of the acoustic stimulus. This phenomenon has been studied at threshold (temporal integration) in normal and impaired ears. Normal ears showed an improved threshold with impulse durations up to 200 msec. In cochlear hearing loss, regardless of pathology, the threshold improvement was reduced. A method to evaluate these changes has been designed (Brief Tone Audiometry). When using this method, a quantitative comparison showed the same reduction in temporal integration in ears with hearing loss, regardless of pathology. By using a loudness balance test, the increase in loudness related to prolongation of the stimulus was investigated (Loudness Summation). Loudness growth was measured at various intensities and the results from normal and hearing-impaired ears were compared. At a given sound intensity both normal and hearing-impaired ears showed the same Loudness Summation, which in turn showed a simple relationship to Brief Tone Audiometry in impaired ears. Physiological and diagnostic aspects of these findings are discussed.