MLD IN CHILDREN - EFFECTS OF SIGNAL AND MASKER BANDWIDTHS

The first aim of this study was to obtain a more detailed picture of t he effect of masker bandwidth (20 Hz to 1000 Hz bandwidth) on the mask ing level difference (MLD) for a 500-Hz signal as a function of listen er age. The results of the pure-tone signal experiment showed that the MLDs of older children differed from adults only for the narrowest ma sker bandwidth. in contrast, children younger than about 7 years of ag e tended to have smaller MLDs than adults at all bur the widest masker bandwidths. These results suggest that the younger the listener, the wider the noise bandwidth must be for MLDs of adult magnitude to be ob served. One interpretation of this effect is that younger listeners re quire relatively great spectral dissimilarity (and, therefore perceptu al dissimilarity) between the signal and masker in order to obtain MLD s of adult magnitude. The second aim of this study was to test this po ssibility by determining the MLD For noise signals in cases where the signal and masker bandwidths were the same. The results of this experi ment showed that the MLDs of children were as large as those of adults when the signal/masker bandwidth was 320 Hz, but were smaller than th ose of adults when the signal/masker bandwidth was 20 Hz. This indicat es that the factor limiting the MLD for narrowband noise in children i s related more to the masker bandwidth than to the perceptual similari ty between the signal and the masker.