Speech recognition with dynamic range reduction: (1) deaf and normal subjects in laboratory conditions

Processing to reduce the dynamic range of speech should increase intelligibility and protect the impaired ear from overloading. There are theoretical and practical objections to using AGC devices to reduce dynamic range. These are overcome by using recently available signal processing employing high frequency carrier clipping. An increase in intelligibility of speech with this HFCC has been demonstrated, for normal subjects with simulated deafness, and for most partially hearing patients. Intelligibility is not improved for some patients; possibly due to their having learned to extract features which are lost. These patients may also benefit after training.