Maturation of auditory stream segregation in school-age children: Effects of signal repetition and frequency predictability.

In multi-source auditory environments, effective listening requires segregation and selective attention to sound streams of interest. School-age children often perform worse than adults under these conditions, but the component skills responsible for child-adult differences are poorly understood. This study measured masked detection thresholds for three groups of children (5-7, 8-10, and 11-13 yrs) and adults, all with normal hearing. The masker was a continuous stream of four-tone bursts, with the frequencies of those four tones randomized for each burst. The signal was a single tone added to one, two, four, or eight sequential bursts. Signal frequency was either 1000 Hz (fixed) or 1000 Hz ± 0.5 octave, randomly selected for each trial (variable). Overall, thresholds were lower for the fixed than variable signal frequency, and thresholds fell with increasing numbers of repeating signal bursts. Signal-frequency variability had differential effects as a function of age group and number of sequential signal bursts. While some aspects of the data are consistent with maturation of the ability to benefit from signal repetition in the context of a random-frequency masker, more research is needed to understand how segregation and selective attention change with age under these stimulus conditions.