In a scheme for mechanical recognition of speakers, it is desirable to use acoustic measures that are related in as direct a manner as possible to the voice characteristics of the unknown speaker and that are minimally affected by irrelevant factors. Acoustic attributes that are dependent on anatomical properties of the speaker's vocal mechanism should be particularly effective ones. Certain phonemes or phoneme features are well suited for displaying speaker-dependent characteristics. For example, aspects of the spectra of /∫/ (high frequency shape), /i/ (shape of the F2-F3-F4 peak), and /m/ (pole-zero interplay and nasal ferments) have been found to be effective. This approach suggests that speaker-recognition procedures should utilize a strategy of measuring only significant features of certain segments of an utterance rather than general measurements over the extent of the utterance. Implementation of this approach in automated speaker-recognition schemes is discussed. [Work supported in part by the National Science Foundation, Air Force Cambridge Research Laboratories, and the National Institutes of Health.]