P. Allen et J. Nelles, DEVELOPMENT OF AUDITORY INFORMATION INTEGRATION ABILITIES, The Journal of the Acoustical Society of America, 100(2), 1996, pp. 1043-1051
The ability of normal-hearing children (aged 4 through 7 years) and ad
ults to integrate information was measured in an auditory sample discr
imination task. On each trial a pair of tonal sequences was played who
se component frequencies were randomly drawn from two equal-variance,
Gaussian distributions with different means. The listeners task was to
identify the sequence drawn from the distribution with the higher mea
n frequency. Performance was first evaluated as a function of the numb
er of components in each sequence. Results showed that discrimination
accuracy improved with increasing age until age 7, at which time perfo
rmance was adult-like. The 7-year-olds and the adults discriminated th
e sequences with increasing accuracy as the sequence length was increa
sed, but the 4- to 6-year-old listeners, as a group, did not. Data wer
e fitted with a model with two free parameters, one representing resol
ution of the components and presumed to reflect peripheral processing,
and another representing central noise added to the decision process
after the component information is combined [R. Lutfi, J. Acoust. Soc.
Am. 86, 934-944 (1989)]. On average, both parameters showed gradual c
hanges as age increased, with adult-like values by 7 years of age. Ind
ividual data however suggest that the changes in central noise with ag
e may be less gradual than the changes in peripheral resolution. In a
second condition, increases in component duration produced improved pe
rformance for the 7-year-olds and the adults, while that of the younge
r listeners remained the same. Fitted parameters suggested improvement
s in component resolution for the older children, with no changes in c
entral noise levels. In a third condition, reducing the overlap in the
distributions improved performance for only a few of several younger
children. This improvement was attributable to lower levels of central
noise. Overall, these results suggest that with increasing age childr
en are better able to discriminate between sounds that are variable an
d have overlapping acoustic characteristics. This age-related improvem
ent may be attributed both to improvements in the ability to resolve t
he components and to reductions in central noise. (C) 1996 Acoustical
Society of America.