Investigation of the relationship between adaptation measured binaurally and monaurally

Recently it has been demonstrated that auditory adaptation can be measured with a monaural technique (Weiler and Friedman, 1973; Weiler and Gross, 1976; Feaster and Weiler, 1975). Because the magnitude of adaptation measured monaurally was nearly identical to that measured binaurally in other experiments, it was assumed that they measured the same phenomenon or phenomena. In the present study the same group of subjects were tested for magnitude of adaptation both monaurally and binaurally. The means were 11.75 dB and 12.17 dB, respectively (N=13). Depsite nearly identical means for the present conditions there was no significant correlation (r=+.27) between the magnitude of adaptation measured under the two conditions. Except for the possibility that individual differences in the ability to do monaural versus binaural tasks may have obscured individual similarities in adaptation, the only other explanation the authors can suggest is that the two techniques measure different aspects of loudness adaptation.