Abstract:

Temporal gap detection (TGD) thresholds measured for silent gaps as a function of the frequency separation between a fixed-frequency pre-gap sinusoidal marker (F[inf 1]) and a variable-frequency post-gap sinusoidal marker (F[inf 2]) may be confounded by off-frequency listening (Formby et al., Aud. Neurosci. 3, 1--20). Evidence of this confounding role comes from simulation experiments with a single-channel envelope detector model. TGD stimulation results suggest that listeners can improve the signal-to-noise ratio and, in turn, TGD performance by adjusting their optimal auditory filter so that it is centered between F[inf 1] and F[inf 2] (Forrest and Formby, Aud. Neurosci. 3, 21--33). Off-frequency listening between F[inf 1] and F[inf 2] may result in underestimates of TGD thresholds that appear as asymmetries in detection performance for F[inf 2] markers presented below and above the F[inf 1] frequency. To obtain more precise estimates of TGD, unaffected by off-frequency listening, performance has been measured and will be reported for three listeners with markers spaced symmetrically and asymmetrically in linear frequency below and above the center frequencies F[inf c]=500 and 4000 Hz. These new results will be compared with an otherwise comparable set of results that were likely confounded by off-frequency listening (Formby et al., Aud. Neurosci. 3, 1--20). [Research supported by NIH.]