Speech evoked auditory brainstem responses: Normative data study

Speech sound is a complex structure with rich harmonic components, dynamic amplitude modulations and rapid spectro-temporal changes. Simple stimuli such as tone-burst, click are insufficient in order to evaluate this complexity. At the brainstem level, auditory brainstem responses should be obtained using speech stimuli to assess the temporal and spectral encoding integrity of the speech stimulus. S-ABR is a valid and reliable tool that provides direct information on how the speech syllabus is coded by the auditory brainstem. It was planned in our study to determine the normative values specific to gender for the frequency domain display which includes the amplitude information of spectral peaks (F0, F1, F2_HF) with time domain display which includes 7 major (V, A, C, D, E, F, O) wave peak latency and amplitude information of the response by taking S-ABR records with artificial /da/ stimulus which has the duration of 40 ms from 30 healthy individuals between 18 and 35, whose native language is Turkish (15 males, 15 females). EEG data were collected from each individual in 5 sessions by using 32-channel headbox and data analyses were conducted in MATLAB software after the records. For each individual having participated in the study, amplitude and latency values of wave peaks were determined. Time domain and frequency domain wave forms were obtained from all participants and it was determined that speech sound are encoded earlier in brainstem in terms of time in females than it is done in males and gender is not effective in energy encoding of fundamental frequency and harmonics of the speech stimulus. It was considered that these data obtained shall form a basis for studies to be conducted for different groups.