Research press release


Nature Human Behaviour

Human behaviour: Baby talk is consistent across 21 cultures

乳児に話しかけたり歌を聞かせたりする際、人々は文化を越えて一貫した方法で、自身の声を変化させていることが明らかになった。この成果を報告する論文がNature Human Behaviour に掲載される。今回の結果は、人々が乳児へ声掛けや歌の聞かせ方には、進化した共通の機能がある可能性があることを示唆している。


今回、Courtney Hiltonたちは、6大陸の21の社会におけるヒトの会話および歌の1615件の録音記録を使用して計算解析を行い、成人と乳児に対する発話で異なる音響的特性を調べた。その結果、音響的特性は、乳児に対する録音と、成人に対する録音の間で一貫して異なることが分かった。例えば、乳児に対する発話の録音は、純粋な音質であり、歌声は控えめで、音声はより高いピッチであった。研究チームが、187か国5万1065人の英語使用者(ただし、参加者の多くは英語を母国語としない)に音声記録を聞かせたところ、聞き手は、発話が乳児にいつ向けられたかについて、偶然以上の確率で正確に推定できることが判明した。


When singing and speaking to young infants, people alter their voices in a way that is consistent across cultures, according to a study published in Nature Human Behaviour

this week. The findings suggest that the way in which humans speak and sing to infants may have a common, evolved function.

Evidence from many animal species shows that vocalizations often have a clear function, such as alarm calls alerting others to nearby predators. Previous research in humans has shown that both lullabies and the way in which parents speak to children have a soothing effect on infants. This suggests that these vocalizations may also have a common function, but cross-cultural evidence for this is limited.

Courtney Hilton and colleagues used a collection of 1,615 recordings of human speech and song from 21 societies across 6 continents, and applied computational analyses to study the acoustic features that differentiate adult- and infant-directed vocalizations. The authors found that acoustic features consistently differed between infant- and adult-directed recordings. For example, infant-directed recordings had purer timbres, songs were more subdued, and speech had a higher pitch. They played the recordings to 51,065 English-speaking people from 187 countries (although, for many of the participants, English was not their primary language), and found that listeners could guess when vocalizations were directed at infants more accurately than by chance.

The results add to our understanding of human speech and song, and suggest that we alter our vocalizations towards infants in a way that is consistent across cultures and widely recognizable, and may have a common function.

doi: 10.1038/s41562-022-01410-x


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