Frequency selectivity and speech intelligibility in noise

Poor speech intelligibility in noise is a major problem for persons afflicted by a sensorineural hearing loss, and this problem is generally not alleviated by a hearing aid. For a typical hearing loss the effective signal-to-noise ratio is degraded by 10 - 15 dB, predominantly due to impoverished frequency selectivity. The critical ratio averaged over speech frequencies is a convenient measure of this component of the auditory handicap. An attempt to improve speech intelligibility in noise through dichotic combfiltering was not successful.