The objective of this project is to develop a preprocessor for speech recognition systems operating in noisy environments. The preprocessor, consisting of a nonlinear inhomogeneous transmission line, will be realized in software, although realization in hardware in FY91 should be possible. More specifically we will:1) Develop a nonlinear transmission line preprocessor that accurately simulates the mechanics of the mammalian inner ear at all sound pressure levels.2) Preprocess speech with the nonlinear transmission line and show that there is a substantial improvement in the signal to noise ratio.3) Assess the desirability and feasibility of implimenting either a digital or analog transmission line on a chip and using it as a preprocessor in the CMU, BBN, or MIT DARPA funded speech recognition systems.