[Basic knowledge on the efficacy of hearing aids depending on the type of hearing impairment for Ear, Nose & Throat specialists].

For Ear, Nose & Throat specialists, the physiological and psychoacoustical deficits related to hearing impairment and the compensatory capabilities of hearing aids are topics of prime importance. In conductive hearing loss, the foremost deficit is decreased audibility, for which hearing aids can compensate almost entirely through the use of level independent gain. In the instance of sensorineural hearing loss, however, the irreversible loss of outer and inner hair cells causes a distorted sound perception, which is particularly troublesome when trying to understand speech in noisy environments. Unfortunately, this distortion cannot be compensated through the use of hearing aids. Nevertheless, in particular listening environments, its effects can be lessened by reducing background noise levels through the use of directional microphones and, to a lesser extent, digital noise reduction. Noise reduction is in many cases also the main effect to improve speech discrimination in retrocochlear hearing loss.