Masking-Level Differences and the Form of the Psychometric Function
James P. Egan, William A. Lindner, Dennis McFadden · The Journal of the Acoustical Society of America · 1965
Psychometric functions were determined for various interaural conditions; these functions show the relation between the detectability and the energy of the signal. The signal was presented in one of two temporal intervals against a continuous noise. The relation between d′ and signal energy E is approximately d′=m(E/N0)k, where m and k are constants for a particular function; 0⩽d′<4. The data indicate that k is constant for a particular observer and that m depends upon interaural conditions. Therefore, MLD=(10/k)log(mi/m0), where mi is the constant for condition i, and m0 corresponds to a reference condition. Consequently, an MLD is independent of the d′ chosen for determination of that MLD. Also, the form of the psychometric function is independent of the interaural condition. This result indicates that “release from masking” may be considered equivalent to a decrease in the noise at the input, rather than reduction in the amount of uncertainty for the observer concerning the parameters of the input. [Work supported by the U. S. Air Force Office of Scientific Research.]