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This paper describes the results of listening evaluations performed on various versions of a tenth order linear predictive coder (LPC-10) which transmits speech at 2400 bits/s and an adaptive predictive coder (APC/SQ) which operates at 9600 bits/s. The algorithms were tested under a variety of different conditions, including various combinations of input background noise, microphone characteristics, transmission channel error rates, and tandeming configurations. The algorithms were tested for intelligibility using the diagnostic rhyme test form four (DRT-IV), and for listener acceptability using the diagnostic acceptability measure (DAM). The tests were run with at least three different speakers for each condition in order to provide an indication of performance of the algorithms over a wide variety of environments.