Thirty listeners used the 9-point speech naturalness rating scale described by Martin, Haroldson, and Triden (1984) to score 1-minute spontaneous speaking samples from 15 normally fluent speakers and 15 stutterers who had completed the initial phases of a prolonged speech treatment program. The same listeners were later asked to judge whether each sample was from a stutterer or from a normal speaker. Reliable listeners identified almost identical numbers of samples from both speaker groups as "normal speakers," but the stutterers received significantly higher scores on the rating scale, indicating that their speech was judged more unnatural sounding. The speech samples incorporated those used in a related study by Ingham and Packman (1978), thus permitting a reevaluation of the findings of that study.

This paper reports the results of two experiments that investigated interval-by-interval inter and intrajudge agreement for stuttered and nonstuttered speech intervals (4.0 sec). The first experiment demonstrated that interval-by-interval interjudge agreement could be significantly improved, and to satisfactory levels, by training judges to discriminate between experimenter-agreed intervals of stuttered and nonstuttered speech. The findings also showed that, independent of training, judges with relatively high intrajudge agreement also showed relatively higher interjudge agreement. The second experiment showed that interval-by-interval interjudge agreement was not significantly different if judges rated 4-sec speech intervals from different samples under three conditions: in random order, separated by 5-sec recording intervals; in correct order, also separated by 5-sec recording intervals; or after brief judgment signals that occurred every 4 sec during continuous samples. The implications of these findings for stuttering measurement are discussed.

Single-subject experiments were conducted with an adolescent and an adult male who stutter to assess the effect on stuttering of changing the frequency of phonation intervals that were within prescribed duration ranges during spontaneous speech. Electroglottograph-identified intervals of phonation were measured using a computer-assisted biofeedback system. Both subjects demonstrated that their stuttering could be controlled by modifying the frequency of phonation intervals within short duration ranges. The experimental effects not only replicated earlier findings but were demonstrated to be independent of changes in speaking rate, or alterations to other intervals of phonation, and produced little disruption to speech naturalness. The theoretic implications of these findings are discussed.

This study was designed to investigate the apparent contradiction between recent reports of physiological and interpersonal research on stuttering that claim or imply high agreement levels, and studies of stuttering judgment agreement itself that report much lower agreement levels. Four experienced stuttering researchers in one university department used laser videodisks of spontaneous speech, from persons whose stuttering could be described as mild to severe, to locate the precise onset and offset of individual stuttering events. Results showed a series of interjudge disagreements that raise serious questions about the reliability and validity of stuttering event onset and offset judgments. These results highlight the potentially poor reliability of a measurement procedure that is currently widespread in stuttering research. At the same time, they have isolated some few highly agreed stuttering events that might serve as the basis for the further development of either event-based or interval-based judgment procedures.

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