Signal-to-noise threshold with and without hearing aid.

We determined the necessary signal-to-noise threshold for 50% sentence discrimination in 130 patients with sensorineural hearing disorders with and without a hearing aid, as well as the minimum monosyllable discrimination loss without hearing aid. A significant correlation coefficient was found to exist of the signal-to-noise threshold with vs. that without hearing aid (r = 0.61), and between the minimum discrimination loss and the signal-to-noise threshold with hearing aid (r = 0.38). These differences in the correlation coefficient indicate that the impairment of speech perception in noise when using a hearing aid is obviously due to the deterioration of the signal-to-noise threshold induced by the hearing loss rather than to the discrimination loss per se.