The feasibility and limitations of speaker adaptation in improving the performance of a "fixed" (speaker-independent) automatic speech recognition system were examined. A fixed vocabulary of 55 syllables is used in the recognition system which contains 11 stops and fricatives and five tense vowels. The results of an experiment on speaker adaptation showed that adult speakers can learn to change their articulations to improve recognition scores and that the adaptation can be achieved in a relatively short time. Several types of articulation change were found useful, including lip rounding, dipthongization, deliberate efforts at voicing and/or frication. Errors between nonlabials were the most difficult to correct by articulation changes. The recognition is based on the extraction of several acoustic features from the speech signal. This is accomplished by a hierarchy of decisions made on carefully selected parameters that are computed from a spectral description of the speech signal. (Author/MT)