Cortical Auditory Evoked Potential: evaluation of speech detection in adult hearing aid users

To analyze the presence of auditory cortical potential and its correlation with psychoacoustic detection of speech sounds as well as the latency of the P1, N1 e P2 components presented in free field in hearing impaired adults with and without amplification.

We evaluated 22 adults with moderate to severe symmetrical bilateral sensorineural hearing loss, regular users of bilateral hearing aids. Speech sounds of low (/m/), medium (/g/) and high (/t/) frequencies were presented in sound field in decreasing intensities of 75, 65 and of 55 dBSPL in free field with and without hearing aids. The used equipment performs automatic statistical detection of the presence of response; forthermore, the latencies of waves P1, N1 e P2 were labeled and the psychoacoustic perception was registered.

The results demonstrated the increased presence of cortical response with hearing aids. We observed the correlation between psychoacoustic perception and automatic detection of 91% for the sounds /g/ and /t/ and ranged from 73 to 86% for the sound /m/. The averages of latencies P1-P2-N1 decreased with both increasing intensity and the use of hearing aids for the three sounds. The differences were significant for the sounds /g/ and /t/ in comparison with and without hearing aids.

There was increase in the presence of cortical auditory evoked potential with hearing aids. Automatic detection of cortical response provided with hearing aids showed 91% agreement with the psychoacoustic perception of the speech signal. In the analysis of latency measures of the P1, N1 and P2 components, it was observed a decrease with the increase of the signal intensity and the use of amplification for the three speech stimuli /m/, /g/ and /t/.