Monaural auditory adaptation of reaction times at .5, 1, and 3 kc/s.

All procedures to measure auditory adaptation depend at least indirectly upon some subjective judgment of loudness, with the exception of the reaction-time (RT) study of Davis and Weiler (Brit. J. Audiol., 1976, 10, 102-106). We used a variant of the Davis-Weiler RT method to measure monaural adaptation at the end of tones of 7 min duration at .5, 1, and 3 kc/s at 60 db SPL, in 62 normal-hearing young adults. Adaptation was expressed as an increase in RT in msec post- vs pre-adaptation in response to a 1-sec probe tone at 10 kc/s at 70 db SPL presented simultaneously with the adapting tone, either (1) in the middle of a 2-sec burst of the adaptation tone prior to the beginning of the 7-min adaptation session (pre-adaptation measure), or (2) during the last seconds (S alerted) of the continuing adaptation tone (post-adaptation measure). Significant pre-post RT differences, collapsed over pre-post measures and over ears, were found at all 3 frequencies (p less than .0001), indicating that the Monaural Heterophonic RT (MHRT) procedure can indeed be used as an objective measure of auditory adaptation. The mean RTs across pre- and post-adaptation measures were 221.9, 217.6, and 228.0 msec in the usual frequency order, significantly different (p less than .0001). Adaptation (i.e., increased RT after 7 min of adaptation) at .5, 1, and 3 kc/s was 36.9, 28.5, and 21.6, respectively. This effect introduced a significant interaction between frequency and adaptation (p less than .001). To transfer from auditory adaptation in reduced RT in msec by the MHRT method to adaptation in reduced phons in db, it will be necessary to construct, perhaps for every S, a table of RTs for a sufficient selection of levels at the relevant frequencies.