Localization and its effect on auditory adaptation

Abstract

The present study was designed to separate localization effects from loudness adaptation effects in order to determine their relative contribution to measured adaptation. Subjects were asked to localize a binaurally presented 400-Hz tone to the midplane by shifting the phase in the comparison ear. The experimental ear was then exposed to a monaurally presented adapting tone for seven minutes and tested for adaptation (dB attenuation). During a postadaptation localization portion of the experiment, the subjects were again asked to localize the binaurally presented tone to midline, with the restriction that the tone directed to the adapting ear remained on continuously. Once relocalization was achieved, the participants were retested for adaptation. The results revealed a significant loudness adaptation level between preadaptation scores and both the postadaptation and the postrelocalization scores obtained. However, no difference was found between the postadaptation and the postrelocalization responses recorded. Hence, it is suggested that adaptation is a loudness effect independent of the binaural interaction effects reflected by localization.