Study of residual otoacoustic emissions in hearing loss with artifact differentiation and physiological responses

ABSTRACT

Purpose

To study the effect of stimulation intensity variation on the responses of distortion products in subjects with sensorineural hearing loss using a new protocol to register the otoacoustic emissions.

Methods

This is a cross-sectional observational study. The following procedures were performed: anamnesis, otoscopy, pure tone audiometry, speech audiometry, tympanometry, distortion product and residual otoacoustic emissions. The residual DPOAE were collected with the Echodia equipment, Elios®. The protocol that was developed allows the variation of frequency and intensity parameters and the responses are analyzed by phase gradient test. Responses recorded in residual otoacoustic emissions were considered “present”, “absent” or “artifact”.

Results

The total included ears was 72. On residual otoacoustic emissions test, at a frequency of 1300Hz and 2000Hz, there was statistically significant difference. By analyzing the average found in the audiometry and the results of residual emissions, only the frequency of 1300Hz showed a statistically significant association in all groups. By correlating the results of the audiometry and the stimulation intensity used to evoke the residual emission, there was positive correlation for the frequencies of 1000Hz and 4000Hz. The “artifact” was mostly recorded in the higher frequencies: 56.2% in 3000Hz and 58.2% in 4000 Hz. Residual EOAPD present was recorded as 18.6% at 1000Hz, 13.4% at 2000Hz, 6.3% at 3000Hz and 7.5% at 4000Hz.

Conclusion

The increased stimulation intensity in the otoacoustic emissions test can aid in the study of residual outer hair cells, as long as a protocol is used to check the correctness of the responses.

Keywords:
Spontaneous otoacoustic emissions; Hearing; Cochlea; Diagnosis; Outer hair cells