Acoustic features underlying internal representation of vocal smile in children

Smile is a key feature in development and can also be heard in the voice. During development, an improvement of vocal emotion recognition abilities has been described along with global neuroanatomical maturation of auditory cortex. While it has been suggested by the predictive coding framework that internal representation refines with age during development, internal representation of vocal smile has not been characterized in children within this specific age range. The present study aims to bridge this knowledge gap by investigating internal representation of vocal smile in children, along with the robustness of this representation. Vocal smile model was assessed in 46 children aged 8 to 12 years and 42 adults. A reverse correlation approach was implemented allowing to distinguish two components of vocal smile model: the acoustic features underlying a vocal smile and the internal representation robustness, quantified as internal Noise. As a group, children display the same internal representation of vocal smile as adults. However, when comparing children’s individual representations to adults one, we demonstrated that within children group, their representation becomes increasingly closer to adults’ template with age. Furthermore, internal noise estimation allows to distinguish two children subgroup, with one subgroup exhibiting a delay in the acquisition of that internal representation. This study provides key insights into the development and variability of emotional voice processing in school-age children.