Age and sex differences in speech FFR suggest early central auditory aging

This study aimed to examine the effects of age and sex on speech-evoked frequency-following response (FFR) latency, amplitude, and spectral features in Turkish-speaking young and middle-aged adults with normal hearing. Moreover, this study aimed to characterize the properties of speech-FFR in native Turkish speakers. A cross-sectional observational design was utilized. Sixty-one right-handed native Turkish speakers with clinically normal hearing were included: Thirty-one were young adults (aged 19-25 years) and 30 were middle-aged adults (aged 40-60 years), with an equal number of males and females in each group. The 40-ms /da/ syllable was presented monaurally to the right ear at 80 dB SPL using alternating polarity. Six wave peaks (V, A, D, E, F, O) were analyzed in both the temporal (latency, amplitude) and spectral (F0, F1, F2) domains. Statistical analyses included independent t-tests, Mann-Whitney U tests, and Spearman's correlation. In the young group, females showed significantly shorter latencies than males across all peaks. In the middle-aged group, this sex difference was limited to A and D peaks. Latencies of D, F, and O waves positively correlated with age, while V wave amplitude negatively correlated with age. No significant sex-related differences were found in amplitude or spectral features. Both age and sex may affect subcortical auditory processing as reflected in Speech-FFR. Latency prolongation and amplitude reduction with advancing age may indicate early neural changes in time domain at the brainstem level, even in adults with normal hearing.These findings suggest potential clinical relevance for Speech FFR and emphasize the need for language specific normative data.