Infants have a good ability to detect brief silent gaps between 2 short identical sound markers (within-channel gap detection), with thresholds between 2 and 11 ms. The present experiment traces the development of temporal resolution for between-channel gaps (i.e., gaps delineated by spectrally disparate markers). This ability appears crucial for the perception of complex stimuli such as speech and is thought to reflect more central auditory processing.
Infants age 6–7.5 months and adults were tested in a between-channel gap detection task using a conditioned head-turn procedure. Gaps were marked by 1- and 4-kHz Gaussian-enveloped sine-tone markers.
Infant gap thresholds were between 30 and 40 ms under conditions in which adult thresholds were between 10 and 20 ms.
Unlike within-channel gap detection, the central temporal processing required for between-channel gap detection is still immature at 6 months of age.