Noise-induced enhancement of envelope following responses in normal-hearing adults.

Measures of signal-in-noise neural encoding may improve understanding of the hearing-in-noise difficulties experienced by many individuals in everyday life. Usually noise results in weaker envelope following responses (EFRs); however, some studies demonstrate EFR enhancements. This experiment tested whether noise-induced enhancements in EFRs are demonstrated with simple 500- and 1000-Hz pure tones amplitude modulated at 110 Hz. Most of the 12 young normal-hearing participants demonstrated enhanced encoding of the 110-Hz fundamental in a noise background compared to quiet; in contrast, responses at the harmonics were decreased in noise relative to quiet conditions. Possible mechanisms of such an enhancement are discussed.