Functioning of olivocochlear bundle and speech perception in noise.
OBJECTIVE
To evaluate the effect of contralateral acoustic stimuli on speech identification scores and to correlate this effect to contralateral suppression of evoked otoacoustic emission.


METHODS
Ten normal-hearing children with good academic performance participated in the study. Speech identification scores were measured in quiet and with different ipsilateral signal to noise ratios in two conditions, with and without contralateral acoustic stimuli. Transient evoked otoacoustic emissions were recorded for 70 dB SPL clicks with and without contralateral acoustic stimuli.


RESULTS
Findings revealed that contralateral acoustic stimuli enhanced speech perception when ipsilateral signal to noise ratios was +10 dB and +15 dB. This enhancement had significant positive correlation with contralateral suppression of OAE.


CONCLUSIONS
The results of the present study support the hypothesis that medial olivocochlear bundle might aid in speech perception in noise, thereby suggesting a possible role of cochlear efferent fibers in hearing. The psychoacoustic measures can be used to evaluate the efferent auditory pathways, where it is not possible to record otoacoustic emissions.
Kumar
U Ajith
UA
Department of Audiology, All India Institute of Speech & Hearing, Mysore, Karnataka, India. ajithajitkumar18@rediffmail.com
Vanaja
C S
CS
D001306:Auditory Pathways / Q000502:physiology; D002648:Child; D004525:Efferent Pathways / Q000502:physiology*; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D018072:Hair Cells, Auditory, Outer / Q000502:physiology*; D006801:Humans; D008297:Male; D009622:Noise / Q000009:adverse effects; D009847:Olivary Nucleus / Q000502:physiology*; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology; D011571:Psychoacoustics; D015203:Reproducibility of Results; D013063:Speech Discrimination Tests / Q000379:methods; D013067:Speech Perception / Q000502:physiology*