Speech recognition in a noisy and reverberant environment with and without earmuffs.

The effect of earmuffs on speech recognition in conditions comparable to an actual environment was studied with the use of sentences, words and nonwords. The speech level was adjusted to 60 and 85 dBA. White noise was used at signal-to-noise ratios (S/N) of 0, +5, and +10 dB. The reverberation times were 2.1 and 1.6 s. In quiet conditions at normal speech level (60 dBA), the perception was better without earmuffs than with them. At a high noise level, equal or better scores were achieved with ear protectors. At high speech and noise levels (85 dBA, S/N 0), the benefit of earmuffs was clearly demonstrated. Also with longer reverberation, the use of ear protectors increased the perception scores, especially at high speech and noise levels.