Effect of adaptation on auditory localization and lateralization

This paper presents a series of experiments on the effect of adaptation in localization and lateralization. Localization measurements were performed, in an anechoic room, on the perceived azimuth of a brief 4-kHz tone, coming from the side of a listener, in the presence of a tone at the same frequency and level coming from the front. The frontal source was turned on first, and left on long enough to induce auditory adaptation at that frequency. It was found that, as the duration of this adaptation period increased, the perceived azimuth of the delayed lateral sound shifted towards the side, away from the actual position of its source. Lateralization measurements, using a diotic inducer and a dichotic test signal, confirmed this finding. A study of the time scale of this adaptation effect shows that it can take between 1 s and 10 s to become settled; but the recovery from adaptation is fairly quick, less than 1 s in the case of our experimental conditions.