AUDITORY DEVELOPMENT IN COMPLEX TASKS OF COMODULATION MASKING RELEASE

Experiments on listeners aged 5 years to adult were conducted to inves tigate the development of comodulation masking release (CMR) under con ditions where auditory grouping could be affected either by the cohere nce of modulation pattern among noise bands, or the temporal asynchron y among bands. The conditions examining CMR when two modulation patter ns were present (each carried by a different set of noise bands) indic ated a similar effect across all age groups. Here, CMR was substantial when the on-signal band (OSB) and six comodulated flanking bonds (FBs ) were presented, decreased when two bands having a second pattern of modulation were added, and then recovered partially when a Further six bonds that had the second modulation pattern were added. In condition s where there was a temporal asynchrony between the OSB and the FBs, t he children typically showed smaller CMRs than the adults. In the case where the OSB preceded the FBs, adults typically showed CMR near zero when the temporal fringe was 50 ms or more, Children usually showed n egative CMRs for such conditions. In the case where the FBs preceded t he OSB, all age groups showed substantial CMRs, but the CMRs of adults were significantly larger than those of the children. The present res ults indicate that the effect of a second, independent modulation patt ern on CMR is similar in children and adult listeners, but that CMR ap pears to be detrimentally affected more in children than in adults whe n there is a temporal asynchrony between the on-signal and flanking ba nds.