Gap detection in school-age children and adults: effects of inherent envelope modulation and the availability of cues across frequency.

Purpose: The present study evaluated the effects of inherent envelope modulation and the availability of cues across frequency on behavioral gap detection with noise-band stimuli in school-age children.

Method: Listeners were 34 normal-hearing children (ages 5.2-15.6 years) and 12 normal-hearing adults (ages 18.5-28.8 years). Stimuli were continuous bands of noise centered on 2000 Hz, either 1000- or 25-Hz wide. In addition to Gaussian noise at these bandwidths, there were conditions using 25-Hz-wide noise bands modified to either accentuate or minimize inherent envelope modulation (staccato and low-fluctuation noise, respectively).

Results: Within the 25-Hz-wide conditions, adults' gap detection thresholds were highest in the staccato, lower in the Gaussian, and lowest in the low-fluctuation noise. Similar trends were evident in children's thresholds, although inherent envelope modulation had a smaller effect on children than on adults. Whereas adults' thresholds were comparable for the 1000-Hz-wide Gaussian and 25-Hz-wide low-fluctuation stimulus, children's performance converged on adults' performance at a younger age for the 1000-Hz-wide Gaussian stimulus.

Conclusions: Results are consistent with the idea that children are less susceptible to the disruptive effects of inherent envelope modulation than adults when detecting a gap in a narrow-band noise. Further, the ability to use spectrally distributed gap detection cues appears to mature relatively early in childhood.