Development of auditory temporal resolution in school-age children revealed by word recognition in continuous and interrupted noise.

OBJECTIVE: The purpose of the study was to investigate the development of one aspect of auditory temporal resolution in normal-hearing school-age children with word recognition in quiet and in spectrally identical continuous and interrupted noise. Typically, listeners experience a perceptual advantage (i.e., a "release from masking") in the interrupted noise relative to the continuous noise at equivalent signal-to-noise ratios (S/Ns). Any release from masking observed with children in the interrupted noise compared with the continuous noise at equivalent S/Ns could be interpreted as evidence for acquired temporal resolution ability. Differences in the amount of release from masking in the interrupted noise between children and adults could be interpreted as development of temporal resolution ability, or lack thereof, as revealed by word recognition in noise. It was hypothesized that word recognition performance would be poorer in children than adults; performance differences would be more pronounced with competition; word recognition performance would reach an asymptote to adult levels sooner in quiet than with competing stimuli; children would demonstrate better performance in the interrupted noise relative to the continuous noise (i.e., display a release from masking); and younger children would experience less release from masking compared with older children and adults (i.e., have less developed temporal resolution).
DESIGN: Eighty normal-hearing children aged 6 to 15 yr and 16 normal-hearing young adults participated. Word recognition performance with Northwestern University-Children's Perception of Speech (NU-CHIPs) stimuli was evaluated with an open-set response mode in quiet and in backgrounds of competing continuous steady-state and interrupted noise at S/Ns of 10, 0, -10, and -20 dB. Both noises were essentially identical in their spectral content and differed only in their temporal continuity.
RESULTS: Performance was better in the interrupted noise at poorer S/Ns, increased with increasing S/N, and improved with increasing age. Younger listeners were more susceptible to noise. They did not experience an equivalent perceptual advantage (i.e., a release from masking) in the interrupted noise at poorer S/Ns (i.e., < 10 dB) and generally required more favorable S/Ns to perform the same as the adult participants. These trends were less pronounced with increasing age. By 8 yr of age, children's performance in quiet equated that of adult levels, but it did not do so in noise until after 11 yr of age.
CONCLUSIONS: As revealed by their NU-CHIPs word recognition performance in continuous and interrupted noises, children's temporal resolving abilities improve in their early school years and reach adult performance levels after 11 yr of age. It was speculated that these changes reflect maturation in their central auditory system.