Fundamental Frequency, Voice Quality, Intensity, and Syllable Rate in Hebrew Child-Directed Speech: Acoustic...

Child-directed speech (CDS) prosodic modifications are well-documented in infancy, but their persistence into middle childhood remains understudied. To address this gap, this study examined developmental changes in acoustic properties of maternal Hebrew speech across early childhood (3-5 years, n = 65) and middle childhood (6-8 years, n = 61). Mothers were recorded playing with their children (CDS) and explaining the activity to an adult (adult-directed speech; ADS). Acoustic analyses measured fundamental frequency (f0), intensity, syllable rate, and voice quality (cepstral peak prominence; CPP). The results revealed significant CDS modifications in both age groups: mothers used breathier voice quality (lower CPP), higher rate, and reduced intensity compared with ADS. Critically, f0 elevation showed significant developmental attenuation: mothers used significantly higher mean f0 when addressing younger children (M = 213.60 Hz, standard deviation [SD] = 39.43) than older children (M = 196.05 Hz, SD = 38.97), whereas syllable rate, voice quality, and intensity modifications did not change significantly across child's age. These findings indicate that CDS remains a distinct register well into school age, characterized by a selective recalibration: while f0 undergoes developmental attenuation, other prosodic features show no significant changes. Future research should examine how these adjustments support the unique developmental requirements of this age group.