Static and dynamic spectro-temporal gap detection

Abstract

Frequency-dependent measures of temporal processing are often based on temporal gap detection measured using sinusoids or bandpass noise. Some natural sounds, such as speech, are better characterized as relatively broadband sounds with low-amplitude portions restricted to narrow frequency regions. The present study reports the perception of analogous stimuli: static and dynamic spectro-temporal gaps embedded in broadband noise. In the first experiment, the temporal gap created a static spectral notch, the duration of which was the independent variable (gap duration in ms) and the width of which was fixed, in separate conditions being either 800 Hz or equal to one or three ERBs (equivalent rectangular bandwidth). The spectral notch was centered at either 800, 1600, 3200, or 6400 Hz. Gap onset relative to stimulus onset varied from 10 to 320 ms. In the second experiment, the temporal gap created a dynamic spectral notch, the lower and upper cutoff frequencies of which varied over the duration of the temporal gap much like a frequency sweep. Experimental parameters included the bandwidth of the notch in octaves and notch center frequency at gap onset and gap offset. The data will be considered in terms of temporal resolution, frequency resolution, and across-channel processing.