Echoes of Early Silence: Medial Olivocochlear Activity in Late-Talking Children

The spectral and temporal components of acoustic input are processed within the central auditory system, contributing to language acquisition and development. This auditory processing depends on the integrated function of the afferent and efferent pathways. Although the effects of afferent auditory pathway disorders on language skills are known, knowledge regarding the role of the efferent auditory system remains limited. This study aimed to investigate the activity of the medial olivocochlear (MOC) efferent system in children with a history of late talking who have subsequently attained age-appropriate language skills.

Twenty-six children with a history of late talking (test group) and 26 typically developing peers (control group), aged 4;0 (years;months) to 7;11, participated in the study. All participants had normal hearing sensitivity, with audiometric thresholds of ≤ 15 dB HL across 250-8000 Hz and bilateral Type A tympanograms. To evaluate MOC activity, contralateral suppression (CS) of transient evoked otoacoustic emissions (TEOAEs) was evaluated using a 65-dB peSPL TEOAE stimulus presented to the right ear and 65-dB SPL broadband noise to the contralateral ear at 1000, 1500, 2000, 3000, and 4000 Hz. The tests were performed in linear mode using a double-probe Otodynamics ILO292-II system.

Analysis of TEOAE measures revealed no statistically significant differences between the two groups at any of the tested frequencies. CS was observed in both groups across all tested frequencies. At 3000 and 4000 Hz, CS was significantly reduced in the test group compared to the control group (p < .05, Cohen's d = 0.72 and 0.68, respectively).

The findings demonstrated reduced MOC activity at higher frequencies critical for speech perception in children with a history of late talking compared to their typically developing peers. This suggests that subtle differences in auditory processing may persist as a long-term consequence of having experienced late talking in early childhood.