A study of the phonetic changes occurring when a speaker attempts to revise an unclear word for a listener focuses on changes made in the sound segment duration to maximize differences between phonemes. In the study, five-year-olds were asked by adults to revise words differing in voicing of initial and final stop consonants; a control group of adults was tested with the same paradigm for comparison. In addition, the children's revision behavior was examined for its relationship to phonemic awareness and reading ability. Results showed that both children and adults made segmental changes in duration while preserving total word duration in elicited word revisions. Voicing distinctions were consistently maintained in revised speech. All subjects appeared to follow a general revision strategy regardless of the source of miscomprehension, altering the duration of segments that relate to the final consonant in the target words rather than and perhaps at the expense of the vowel's duration. Other changes such as amplitude, fundamental frequency, and spectral changes were not measured. Illustrative oscillograms and graphs are included. (MSE)