Effect of Lateralization, Age, and Sex on Frequency Following Response in Children: Neural Speech Encoding to a 170 ms [da] Stimulus

Central auditory processing efficiency is considered a predictor of how well children can learn to read, with the Frequency Following Response (FFR) serving as a sensitive biomarker of neural speech encoding ability. However, data regarding the 170 ms [da] stimulus in children who are native speakers of Brazilian Portuguese (BP) remain limited. This study investigated FFR results in 37 typically developing, normal-hearing children aged 8 to 10 years. Participants underwent audiological, behavioral, and academic performance screenings, followed by monaural FFR recording (using a 170 ms [da] stimulus at 80 dBnHL). Linear mixed models (LMM) were used to examine the effects of age, sex, and ear on the latencies of waves V, A, D, E, F, and O. The analysis revealed a medium effect size for waves D, E, and F, regarding the Ear factor, though statistical significance was specifically observed for wave E. For this wave, sex was also associated with a medium effect size, characterized by longer latencies in female participants. While the results for age did not reach broad statistical significance, the presence of medium effect sizes in wave E may suggest ongoing refinement of neural synchrony and asymmetric maturation during this developmental period. This study contributes to the characterization of neural speech encoding in the Brazilian Portuguese-speaking children and may support future investigation involving auditory processing disorders and learning difficulties.