DEVELOPMENT OF TEMPORAL RESOLUTION IN CHILDREN AS MEASURED BY THE TEMPORAL-MODULATION TRANSFER-FUNCTION

Temporal modulation transfer functions (TMTFs) were measured in listeners aged 4 years to adult in order to characterize the development of temporal resolution in children. Four age groups were tested, 4-5 years of age, 6-7 years of age, 9-10 years of age, and adult. Sensitivity to sinusoidal modulation of a noise carrier (a bandpass noise from 200-1200 Hz) was determined for modulation frequencies of 5, 20, 100, 150, and 200 Hz. The data from all listeners indicated decreasing sensitivity to modulation as a function of increasing frequency of modulation. Time constants were derived from the 3-dB down points of functions that were fitted to the data. No age effects were observed for the derived time constants. However, sensitivity to modulation was found to be reduced in the children 4-5 and 6-7 years of age, as compared to adults, and in the children 4-5 years of age as compared to children 9-10 years of age. The agreement of time constant across all age groups was interpreted as indicating that the peripheral encoding of the temporal envelope is probably adultlike in children aged 4 years and above; however, young children appear to be relatively inefficient in processing the information underlying modulation detection.