Abstract:

Detection thresholds for a tone in an unfamiliar tonal pattern are greatly elevated under conditions of masker uncertainty [D. L. Neff and D. M. Green, Percept. Psychophys. 41, 409--415 (1987)]. The present experiment was undertaken to determine whether a similar result is obtained when the masker is a familiar sound. Fifty common environmental sounds served as familiar maskers (e.g., dog bark, door slam, phone ring, etc.). Fifty Gaussian noise samples served as unfamiliar maskers. The magnitude and phase spectra of each masker were analyzed into 906 spectral components. Masker uncertainty was introduced by using fewer than 906 components to synthesize each sound, and by selecting the frequencies of these components at random on each presentation. Masked thresholds for a 1.0-kHz signal were obtained using an adaptive, two-interval, forced-choice procedure. Results with noise replicate earlier results showing largest elevations in threshold for 10--20 spectral components. Results with familiar sounds showed a similar pattern but with even larger elevations in threshold. Trial-by-trial analyses showed a small detection advantage for sounds rated as highly familiar by listeners. Overall the results fail to provide strong evidence that listeners use stimulus familiarity to overcome the effects of masker uncertainty. [Research supported by NIDCD.]