When a person listens to speech corrupted by noise or other adverse environmental factors, speech intelligibility may be impaired slightly or not at all. The same corrupted speech, after being vocoded, often causes drastic intelligibility loss. The is due to the fact that the human peripheral auditory system is a superior signal processor to that of the vocoder. This report is based on the premise that a vocoder analyzer that better resembles the peripheral auditory system would function in a superior manner to present-day vocoders. Topics include reviews of speech enhancement techniques, perceptual analysis of diagnostic rhyme test data, a brief description of the peripheral auditory system and an outline of proposed psychophysical tests. The final section is devoted to a discussion of some preliminary work on computer simulation of an auditory model.