Abstract
One of the major complaints of hearing aid users is their inability to understand speech in noisy environments. We have developed a new hearing aid which has selective amplification-ability in the speech frequency band utilizing a compression amplifier which automatically compresses the lower frequency range as a function of the level and spectrum of the environmental noise. The output of the LPF is passed through a compression amplifier and then mixed with the signal passing through the HPF.
The results of speech discrimination tests using speech-in-noise on 70 hearing impaired subjects showed improvement in word discrimination scores in noise of over 15 % for 51 of 54 sensorineural subjects. On the other hand, results on 16 subjects with conductive or mixed hearing impairments showed scores between 75 and 100 which is no improvement at all, but their opinions were favorable and it proved that the sound was more natural and quiet compared with the conventional AGC hearing aids.
