A computer editing technique was used to remove varying amounts of voicing from the syllable-final closure intervals of naturally produced tokens of /p epsilon b, p epsilon d, p epsilon g, pag, pig, pug/. Vowels for all six syllables were approximately the same duration, and the final release bursts were retained. Identification results showed that voiceless responses tended to occur in relatively large numbers when all of the closure voicing and, in most cases, a portion of the preceding vowel-to-consonant (VC) transition had been removed. A second experiment demonstrated that removal of final release bursts had very little effect on the identification functions. Acoustic measurements were made in an attempt to gain information about the acoustic bases of the listeners' voiced-voiceless judgments. In general, stimuli that subjects tended to identify as voiceless showed higher first-formant offset frequencies and shorter intensity decay times than stimuli that subjects tended to identify as voiced. However, for stops following /i/ and /u/ these acoustic differences were relatively small. We were unable to find a single acoustic measure, or any combination of measures, that clearly explained the listeners' voiced-voiceless decisions.

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This study describes the acquisition of the entire fricative and affricate sound classes by a child with a disordered phonological system and other co-occurring conditions. Pretreatment, the participant, age 5;3 (years; months), produced homorganic stops for all fricatives and affricates. Two fricatives, /v/ and /z/, were taught one at a time in the word-initial position, first by imitation and then in minimally paired words to test hypotheses regarding the generalization of the features [continuant] and [strident] across word positions and sound classes. The 26-week treatment followed cognitive-linguistic principles and resulted in reorganization of the sound system to include the fricative and affricate sound classes.

To determine whether any systematic differences occur as a result of using spectrograms versus digital oscillograms to make durational measurements, a number of temporal features (e.g., voice onset time, vowel duration, and consonant closure duration) for 3 speakers were independently measured by 2 different investigators. Both experimenters measured the same intervals with conventional spectrograms and with digital oscillograms, separated by at least a 2-week interval. Oscillograms tended to reveal slightly longer vowel durations and more voicing during consonant closure, while spectrograms evidenced slightly longer consonant closure durations. In general, variations between the two types of instrumentation were no more than 8 to 10 ms and are, therefore, of primary consequence only for studies in which quite small temporal differences are critical.