Abstract:
The age at which the magnitude of the masking level difference (MLD) reaches adult levels depends partly upon masker bandwidth (BW). For wider BWs, children perform like adults by 5--6 years of age. For narrow BWs, adult-like performance is not reached until an older age. To examine this age dependence further, this study measured the MLD for a 500-Hz tone as a function of masker BW in a group of 20 children aged 5--10 years, and in a group of 10 adults. Masker BWs were 20, 40, 80, 160, 320, and 1000 Hz, centered at 500 Hz. The MLDs of the children were generally smaller than those of the adults for BW = 20 Hz. Children over 7 years of age had adult-like MLDs for all BWs (greater than or equal to) 40 Hz. The youngest children did not reach adult levels until BWs (greater than or equal to) 320 Hz. To determine whether the smaller MLDs at narrow BWs were due to the perceptual similarity between the masker and the signal, MLDs were also measured in conditions where both masker and signal had BWs = 20 or 320 Hz. Children under 8 years of age showed the same MLDs for both BWs. Older children and adults had larger MLDs for the narrow BW. [This work supported by NIH NIDCD.]