Articulation rate and the duration of syllables and stress groups in connected speech.

Further analyses have been made on readings of two scripts by six talkers [T. H. Crystal and A. S. House, J. Acoust. Soc. Am. 72, 705-716 (1982); 84, 1932-1935 (1988); 83, 1553-1573 (1988)]. Durations of syllables and stress groups are compared to earlier data and various pertinent published reports, and are used to evaluate reports of articulation rate variability. The average durations of syllables of different complexity have a quasilinear dependency on the number of phones in the syllable, where the linear factor and the vowel durations are functions of stress. The duration of stress groups has a quasilinear dependency on the number of syllables and the number of phones. It was found that variability of articulation rate, measured as the average syllable duration for interpause intervals (runs), is not random, but is the natural consequence of the content of the run. Durations of comparable runs of different talkers are highly correlated. Major determinants of average syllable duration are the average number of phones per syllable and the proportion of either + stress phones or + stress syllables in the run.

A note on the variability of timing control.

Analyses of duration data measured from connected-speech signals for three "slow" and three "fast" adult talkers produced, for various sound categories and talkers, mean values and standard deviations that demonstrated strong functional relationships. These relationships preclude the use of the two measurements as independent descriptors of speech production. Typical distributions are shown. The implications of these data for the interpretation of the standard deviation of duration distributions in studies of the development of motor control and skilled action in children are discussed.

Segmental durations in connected speech signals: preliminary results.

The data base, methods for a study of the durations of phonetic units in connected speech, and some preliminary results are described. From readings of two scripts by many talkers, two sets of seven talkers each were selected, based on total reading time, to form a fast group and a slow group of talkers. Using computer graphics and digital playback procedures, the recordings were segmented into breath groups and pauses, and the first four sentences in each script were segmented into phones. The hold and release (that is, plosion and/or frication) portions of stops were identified and measured; less than 50% of the stops included releases. To establish the usefulness of the data base, the first-order statistics of the phonetic segments were determined, and a variety of durational characteristics were compared to existing reports. Analysis of number of breath groups, phonation time, and pause characterized the difference between so-called average fast and average slow talkers; however, no script-independent measure of these variables was found which would accurately predict the classification of individual talkers. The mean durations of various phonetic categories showed essentially the same percentage change when the fast and slow talkers were compared. Preliminary analyses of contextual influences on durations showed some expected changes, and also indicated that certain traditional predictions may not hold for informal connected speech. Gamma functions were fitted to the distributions of durations of various gross categories.

Reflections on a double negative: misarticulation and inconsistency.

The results of recent work on the so-called inconsistency of misarticulations of certain speech sounds are examined in terms of previous knowledge available to speech pathologists and of some of the contributions attributable to more recent procedures and points of view. It is concluded that some current descriptions of articulation which are concerned primarily with physiological constraints can mislead clinicians, and that maximally useful descriptions of the influences operating on the production of speech sounds must include linguistic constraints as well.