Investigation of cochlear microphonics recorded with different stimulus types

Electrocochleography (ECochG), one of the first defined tests under auditory evoked potentials, is a total electrical response of inner and outer hair cells inside the cochlea and auditory nerve record technique to the presence of an acoustic stimulus. These records can be used in Meniere disease and auditory neuropathy spectrum disorder diagnosis, intraoperative monitoring. In addition, the presence of cochlear microphonics plays a crucial role in auditory neuropathy spectrum disorder diagnosis. In our study, healthy individuals were tested with extratimpanic electrocochleography record method via Click and LS CE-Chirp stimulus, and the results were compared to the age, sex, and noise sensitivity categories.

This study had executed at Başkent University, Faculty of Health Sciences Audiology laboratory. The study group consisted of 42 volunteers between 18 and 40 years old. To understand the suitability of volunteers, pure tone audiometry, tympanometry, and transient otoacoustic emission tests were performed. Individuals with no hearing loss were tested with 100 dBnHL intensity level via click and LS CE-Chirp stimulus. The obtained values were statistically evaluated in the SPSS 23.0 program in accordance with the data distribution. An independent sample t-test was used for data showing normal distribution, and Mann-Whitney U test was used for data not showing normal distribution. The level (p < 0.05) was considered statistically significant for all analyses performed.

Cochlear microphonic amplitudes recorded with click and LS CE-Chirp stimuli were higher in males than in females (p = 0.051 and p = 0.001, respectively). When the age groups were evaluated, no difference was observed in the CM amplitudes obtained with both click and LS CE-Chirp stimuli. There was no correlation between age and CM amplitudes. Additionally, it was determined that the CM amplitudes recorded with the click stimulus in individuals with noise sensitivity were higher than those without noise sensitivity (p = 0.051).

It is thought that the ECochG amplitudes of different gender, different age, and different noise sensitivity, which are the results of our study, can be used in the diagnosis of diseases such as auditory neuropathy spectrum disorder.