The development of voluntary emotional communication in children's non-verbal vocalizations

Non-verbal vocalizations, such as cries, laughter, or groans, are crucial for conveying emotions and social signals, providing a unique lens into affective encoding and perception in humans. In human adults, voluntary vocal modulation—the intentional adjustment of acoustic parameters like voice pitch, intensity, or timbre—is well-established as a mechanism for amplifying or attenuating emotional signals, thereby shaping social interactions and hierarchies. However, its development in children remains largely underexplored. To address this gap, I will report the results of a voice production study investigating whether children (N = 144) aged 3.2–10.5 years can voluntarily modulate the valence (positive versus negative) and arousal (low versus high) of different emotions expressed through non-verbal vocalizations, including the emotions joy, amusement, pride, pain, sadness, disgust, anger. I also explore how these abilities develop with age and differ by sex. Using acoustic analyses targeting key voice parameters (e.g., fundamental frequency (fo), duration, roughness), we hypothesized that children exhibit early emerging modulation skills that are refined with age due to advancements in vocal tract control and emotional regulation. By elucidating the developmental trajectory of non-verbal emotional vocalizations, this study illuminates the foundations of social communication and emotional development.