Alterations in cochlear function after exposure to short term broad band noise assessed by otoacoustic emissions.
BACKGROUND
Sudden or chronic exposure to sound alters the functioning of cochlea. This results in temporary or permanent alteration of functioning of cochlear cells. Alteration of functioning of outer hair cells (OHC) of cochlea following exposure to noise can be assessed by measurement of transient otoacoustic emissions (TEOAE). Such a measurement is of great clinical importance in early detection of the damage to the OHC.


OBJECTIVE
In this study we aim to study effect of noise on outer hair cell function by studying the changes in TEOAE's amplitude following exposure to short term broad band noise in healthy volunteers.


METHODS
Twenty volunteers' ten males and ten females participated in the study. They underwent pure tone and impedance audiometry to rule out ear pathology. Then pre-exposure TEOAE's were recorded. After that they were exposed to broad band noise for two minutes. After gap of five minutes again TEOAE's were recorded. Pre and post exposure amplitude of TEOAE's was analysed statistically.s


RESULTS
There was statistically significant difference between pre exposure and post-exposure amplitude of TEOAE's. Pre and post exposure values for A & B amplitudes showed p-value of 0.0001 whereas values for A-B amplitude showed p-value of 0.0001.


CONCLUSIONS
Measurement of TEOAE's can detect early changes in the functioning of outer hair cells which cannot be picked by routine pure tone audiometry. Thus they can be used in assessing early changes in cochlear function following exposure to noise in individuals exposed to sudden noise or working in noisy environments. Thus preventive methods to reduce the noise induced hearing loss in such individuals can be implemented.
Associate Professor, Department of Ear, Nose and Throat, S.Nijalingappa Medical College and Shree Hanagal Kumareshwar Hospital & Research Center , Karnataka, India .
Chandrashekharayya
C
S H
Audiologist and Speech Therapist, Department of Ear, Nose and Throat, S.Nijalingappa Medical College and Shree Hanagal Kumareshwar Hospital & Research Center , Karnataka, India .
Prasen
P
Reddy
Assistant Professor, Department of Biochemistry, S.Nijalingappa Medical College and Shree Hanagal Kumareshwar Hospital & Research Center , Karnataka, India .
Kavitha
K
M M
Assistant Professor, Department of Ear, Nose and Throat, S.Nijalingappa Medical College and Shree Hanagal Kumareshwar Hospital & Research Center , Karnataka, India .
Prabhu
P
Khavasi
Professor and HOD, Departmentof Ear, Nose and Throat, S.Nijalingappa Medical College and Shree Hanagal Kumareshwar Hospital & Research Center , Karnataka, India .
S S
SS
Doddamani
Broad band noise; Temporary threshold shift; Transient evoked otoacoustic emissions