Organization and discrimination of repeating sound sequences by newborn infants.

A study was conducted to determine whether newborn infants organize auditory streams in a manner similar to that of adults. A series of three experiments investigated the ability of 3- to 4-day-old infants to discriminate repeated rising and falling four-tone sequences in two configurations of source timbre and spatial position. It was hypothesized that if the sequences were organized into two auditory streams on the basis of timbre and spatial position, one of the configurations should be discriminable from its reversal while the other should not. The sequences were tested with different pitch and temporal intervals separating the tones. Sequences were discriminated for the first configuration by adults at both fast tempo/small interval and slow tempo/large interval combinations, while only the latter was discriminated by newborns as measured with a non-nutritive high-amplitude sucking paradigm. Neither adults nor infants could discriminate the sequence reversals for the second configuration. The results suggest that newborn infants organize auditory streams on the basis of source timbre and/or spatial position. They also suggest that newborns have limits in temporal and/or pitch resolution when discriminating tone sequences.