Acoustical regularities in infant-directed vocalizations worldwide

Abstract

Adults often differentiate their song and speech between infants and other adults. Why? Is this a product of just some cultures or does it reflect a universal part of human vocal communication and human cognition? On the latter hypothesis, infant directed-song might regularly exhibit certain features across cultures, including high redundancy and repetition, high signal-to-noise ratios, and superb vowel prolongation and stability compared to adult-directed song. We built a corpus of 1614 recordings of infant- and adult-directed singing and speech produced by 411 people living in 20 societies, including hunter-gatherers and subsistence farmers. Each participant provided examples of each of the four vocalization types. Using exploratory and confirmatory analyses, we show that the acoustical features of infant-directed song and speech are universally distinct from adult-directed song and speech, especially in terms of the phonetic space of their formants, their general rhythmic structure, and their pitch range attributes.Adults often differentiate their song and speech between infants and other adults. Why? Is this a product of just some cultures or does it reflect a universal part of human vocal communication and human cognition? On the latter hypothesis, infant directed-song might regularly exhibit certain features across cultures, including high redundancy and repetition, high signal-to-noise ratios, and superb vowel prolongation and stability compared to adult-directed song. We built a corpus of 1614 recordings of infant- and adult-directed singing and speech produced by 411 people living in 20 societies, including hunter-gatherers and subsistence farmers. Each participant provided examples of each of the four vocalization types. Using exploratory and confirmatory analyses, we show that the acoustical features of infant-directed song and speech are universally distinct from adult-directed song and speech, especially in terms of the phonetic space of their formants, their general rhythmic structure, and their pitch ran...