The neural encoding of speech sound begins in the auditory nerve and travels to the auditory brainstem. Non speech stimuli such as click or tone bursts stimulus are used to check the auditory neural integrity routinely. Recently Speech evoked Auditory Brainstem measures (ABR) are being used as a tool to study the brainstem processing of Speech sounds. The aim of the study was to study the Speech evoked ABR to a consonant vowel (CV) stimulus. 30 subjects with normal hearing participated for the study. Speech evoked ABR were measured to a CV stimulus in all the participants. The speech stimulus used was a 40 ms synthesized/da/sound. The consonant and vowel portion was analysed separately. Speech evoked ABR was present in all the normal hearing subjects. The consonant portion of the stimulus elicited peak V in response waveform. Response to the vowel portion elicited a frequency following response (FFR). The FFR further showed a coding of the fundamental frequency (F0) and the first formant frequency (F1). The results of the present study throw light on the processing of speech in brainstem. The understanding of speech evoked ABR has other applications both in research as well as in clinical purposes. Such understanding is specially important if one is interested in studying the central auditory system function.

Video head impulse test (vHIT) aids to assess all three pairs of semi-circular canals (SCCs) separately and can be utilized to find out the exact site of lesion in any three SCCs by measuring vestibulo ocular reflex (VOR) gain. VOR gain value of vHIT has been used to diagnose different vestibular pathologies. Hence, it is important to establish the test-retest reliability of the VOR gain parameters before it could be administered to the patients. Therefore, the aim of the present study was to obtain VOR gain data, correlate all planes in both sides of head (right and left) and assess the test-retest reliability of VOR gain measure using vHIT in 25 normal young adult participants. Video head impulse test tests were carried out with prototype ICS impulse video goggles with a camera speed of 250 frames/s, recording motion of the right eye in all three planes (lateral, right anterior left posterior, left anterior right posterior) for all the participants. vHIT testing was repeated for all the participants after 15 days. Statistical analysis revealed that mean VOR gain for right horizontal canal was higher than the left horizontal canal; right anterior canal was higher than left anterior canal and left anterior was higher than right posterior canal. Horizontal canals have more gain compared to anterior and posterior canals. There was no significant difference between the VOR gain of session 1 and session 2 for each SCC.

No abstract

Presence of higher asymmetry ratio in cVEMP and vHIT test results plus refixation saccades to stabilize the gaze in vHIT can suggest some amount of vestibular anomalies in individuals with motion sickness.

c l i n i c a l e p i d e m i o l o g y a n d g l o b a l h e a l t h 5