TY - JOUR

T1 - A systematic review and Bayesian meta-analysis of the acoustic features of infant-directed speech

AU - Cox, Christopher

AU - Bergmann, Christina

AU - Fowler, Emma

AU - Keren-Portnoy, Tamar

AU - Roepstorff, Andreas

AU - Bryant, Greg

AU - Fusaroli, Riccardo

PY - 2023/1

Y1 - 2023/1

N2 - When speaking to infants, adults often produce speech that differs systematically from that directed to other adults. To quantify the acoustic properties of this speech style across a wide variety of languages and cultures, we extracted results from empirical studies on the acoustic features of infant-directed speech. We analysed data from 88 unique studies (734 effect sizes) on the following five acoustic parameters that have been systematically examined in the literature: fundamental frequency (f 0), f 0 variability, vowel space area, articulation rate and vowel duration. Moderator analyses were conducted in hierarchical Bayesian robust regression models to examine how these features change with infant age and differ across languages, experimental tasks and recording environments. The moderator analyses indicated that f 0, articulation rate and vowel duration became more similar to adult-directed speech over time, whereas f 0 variability and vowel space area exhibited stability throughout development. These results point the way for future research to disentangle different accounts of the functions and learnability of infant-directed speech by conducting theory-driven comparisons among different languages and using computational models to formulate testable predictions.

AB - When speaking to infants, adults often produce speech that differs systematically from that directed to other adults. To quantify the acoustic properties of this speech style across a wide variety of languages and cultures, we extracted results from empirical studies on the acoustic features of infant-directed speech. We analysed data from 88 unique studies (734 effect sizes) on the following five acoustic parameters that have been systematically examined in the literature: fundamental frequency (f 0), f 0 variability, vowel space area, articulation rate and vowel duration. Moderator analyses were conducted in hierarchical Bayesian robust regression models to examine how these features change with infant age and differ across languages, experimental tasks and recording environments. The moderator analyses indicated that f 0, articulation rate and vowel duration became more similar to adult-directed speech over time, whereas f 0 variability and vowel space area exhibited stability throughout development. These results point the way for future research to disentangle different accounts of the functions and learnability of infant-directed speech by conducting theory-driven comparisons among different languages and using computational models to formulate testable predictions.

KW - Acoustics

KW - Bayes Theorem

KW - Humans

KW - Infant

KW - Phonetics

KW - Speech

KW - Speech Acoustics

U2 - 10.1038/s41562-022-01452-1

DO - 10.1038/s41562-022-01452-1

M3 - Review

C2 - 36192492

VL - 7

SP - 114

EP - 133

JO - Nature Human Behaviour

JF - Nature Human Behaviour

SN - 2397-3374

IS - 1

ER -