The effect of coclear reserve on extratympanic electrocochleography values with normal hearing and mild hearing loss individuals

Electrocochleography (ECoG) is a method for recording the electrical potentials of cochlea and peripheral part of auditory nerve. Technically; electrical response of cochlea and auditory nerve recorded after a given an acoustic stimuli. This study was conducted in Baskent University Hospital, Ear- Nose- Throat department. Volunteers with normal hearing and mild hearing loss were involved in this study. All participants'were undergone ENT examination, audilogical testing and vestibular tests. Electrocochleography applied to participants and SP/AP values were recorded. Eightyeight participants, 50 (56,8%) female and 38 (43,2%) male, were involved in this study. Sum of 164 ears, 118 (72%) controls and 46 (28%) with mild hearing loss, 82 (50%) right and 82 (50%) left ears, were evaluated. Ears involved in this study belongs to 95 (57,9%) females and, 69 (42,1%) males. Mean age of participants was 37,28±7,983 years, control group was 36,49±8,001 years and median age of study group was 38(26-50) years. Hearing thresholds of 125, 250, 500, 1000, 2000, 4000, 6000 ve 8000 Hz of control group were 10, 10, 5, 5, 5, 5, 10, 5 dB respectively and study group were 20, 20, 20, 25, 30, 30, 30, 25 dB respectively. Both groups underwent distortion production otoacoustic emission (DPOAE) for objective evaluation of hearing level. Mean SP/AP value of normal ears was 0,37±0,149 which shows normal distribution and mean SP/AP value of ears with mild hearing loss was 0,49±0,149 that does not show normal distribution. Mean SP/AP value of all ears participated in this study was 0,40±0,159. Difference between study and control group of SP/AP values distribution were with 95% confidence statistically significant (Mann Whitney z=3,889, p<0,001). Correlation between hearing levels and SP/AP values analysed and found no correlation in both groups. Data of this study will be used in further studies of Baskent University ENT Department as normative values.