An assessment of two amplitude-compression hearing aid systems, especially in high ambient noise

A critical test of the suitability of amplitude compression in hearing aid design must look at the performance of such devices with high levels of background noise. A series of tests was carried out, using both normal and hearing-impaired subjects and word-list test material. The results favour some forms of amplitude compression, even under these critical conditions. However, nonlinear compression ('Carrier Clipping') can reduce the signal-to-noise ratio to unity under adverse conditions. Under these circumstances, such compression impairs performance, though in most situations, it is beneficial.