Gloria J. Borden

Acoustics of stop consonant-vowel relationships during fluent and stuttered utterances☆

Abstract Acoustic duration measures were made on the stop-gap, voice onset time (VOT), and vowel portions of the utterance [tu] in the context “425” as spoken ten times or more by five normal speakers, four mild stutterers, and four severe stutterers. The fluent utterances of the severe stutterers were significantly longer than those of normal speakers on stop-gap and vowel durations but not on voice onset times. Despite the slower speech of the severe stutterers, indications of normalization were found in the relatively stable consonant-to-vowel ratios across groups and in the lack of any significant differences of segment durations as a percentage of total utterance times. Normal speakers and mild stutterers showed an inverse relationship between stop-gap and VOT measures across speakers, but severe stutterers did not maintain this relationship for either fluent or stuttered tokens, nor did a mild stutterer suspected of covert stuttering. Stop-gap durations increased while VOTs stayed within normal limits for fluent tokens. For stuttered tokens, some subjects increased the stop-gap and some the VOT depending upon the location of the block. Abnormal gap to VOT ratios may serve to detect convert stuttering.

Temporal Aspects of Articulatory Movements for /s/-Stop Clusters

Cinefluorographic tracking of pellets on the tongue body, tongue tip, jaw, and lips of three subjects indicates that there are certain basic strategies used for initial /sp/, /st/ and /sk/ clusters. The data reveal an economy of effort in tongue movement, and support the concept of the tongue as a multiple articulator. In addition, the shorter fricative duration of /s/ before /p/ is seen to be a result of early lip closure relative to the occlusions for /st/ and /sk/, which are delayed due to tongue involvement with the /s/.

Use of Feedback in Established and Developing Speech

Publisher Summary This chapter discusses the use of feedback in established and developing speech. The chapter presents a current view of how speech control may operate in skilled and non-skilled speakers. The chapter also reviews evidence for at least three levels of information flow that can be used to direct the production of speech: (1) internal feedback, (2) response feedback, and (3) external feedback. Internal feedback is made possible by circuits among the cerebrum, midbrain, and cerebellum of the brain. Response feedback from much of the speech musculature is relayed from muscle spindles and, added to any information from tendon and joint receptors, is thought to form the complex sensation of movement and position. External feedback through the auditory and tactile systems yields knowledge of results to the speaker—knowledge that can be used for fine-tuning of the speech signal or for the correction of errors.

Coordination of Laryngeal and Supralaryngeal Behavior in Stutterers

In 1971 Van Riper suggested that the temporal disruptions in speech which constitute stuttering result from the speaker possessing a deficient timing mechanism for speech. Recently Kent (1984) has reiterated this idea by postulating that the essence of stuttering is a reduced ability to generate temporal programs. A related explanation of stuttering is expressed in the discoordination hypothesis advanced by Perkins and colleagues (1976). According to the discoordination hypothesis, stuttering results from a speaker’s difficulty in coordinating phonation with articulation and respiration. This hypothesis expresses in weakened form, the view that the larynx has a central role in precipitating moments of stuttering, a notion which prompted much research in the 1970s. In general, these studies have left the question of laryngeal focus unresolved, although they have revealed evidence of a strong laryngeal component in stuttering (Conture, McCall & Brewer, 1977; Freeman & Ushijima, 1978). In order both to better understand the nature of speech timing in stutterers and to resolve the laryngeal focus question, it is appropriate to study how the three major speech systems interact or coordinate when stutterers are speaking.

Electroglottographic and acoustic waveforms of voice onset in stutterers

The first few glottal pulses in the stuttered and fluent tokens of voiced utterances by stutterers were analyzed and compared with the initial voice pulses in the same utterances by nonstutterers. Signals analyzed were the impedance changes across the glottis during voice initiation via electroglottography (EGG) and the acoustic waveforms. In single‐cycle analysis of vocal fold vibration, normal speakers evidenced abrupt decrease in impedance with increasing vocal fold contact, and a more gradual increase in impedance as the folds opened. Stutterers, when perceived as fluent, followed the same pattern as normals. Extremely aberrant EGG patterns often accompanied stuttering episodes, with idiocyncratic strategies revealed for breaking the stuttering block. The envelope for the first EGG cycles differed from normal for some stutterers. Some of the severe stutterers showed patterns of gradual buildup of EGG amplitude after a block, whereas the mild stutterers and normal controls showed a more abrupt envelope...

Lip/jaw coordination with larynx in the speech of stutterers

Laryngeal movements were inferred from slow and fast (filtered) impedance changes recorded by an electroglottograph and lip/jaw movements from the deflections of an LED attached to the lower lip. Stutterers and control subjects repeated two, four‐digit numbers five times each or until they were judged to be fluent. The interactions of the lip/jaw lowering at the release of the [f] constriction in the words “four” and “five” with vocal fold adduction for the vowel and the onset of voicing were analyzed by making selected temporal measures in both the displacement and the velocity traces. Results of the data analyzed thus far indicate functional relationships: i.e., the lip/jaw system coordinates with vocal folds for the [f] by closely timing oral constriction release with maximum vocal fold opening, and for the vowel by closely timing peak velocity of lip/jaw opening with peak velocity of vocal fold adduction. Stutterers show aberrant laryngeal‐supralaryngeal interactions as well as instances of “normal” c...

Coordination of fingers and speech

Contact between fingers and thumb on a task of counting on ones fingers was related to lip/jaw and laryngeal movements while simultaneously counting aloud. Finger contacts were measured from the onset of a voltage produced as the contact completed a circuit. Speech movements were inferred from the deflections of a LED attached to the lower lip of the speaker and from the slow and fast (filtered) impedance changes recorded by an electroglottograph. Subjects counted 20 four‐digit number series composed of the numbers 2, 3, 4, and 5. They were instructed to simultaneously count aloud and on their fingers, the second task providing more uncertainty than the first. Results showed that subjects timed finger contacts most closely with the movements of lip/jaw lowering and vocal fold adduction preparatory to voicing, rather than with voicing itself. These results add physiological evidence to acoustic data previously reported by G. Allen [Lang. Speech 15, 72–100 (1972)], K. Rapp [Pap. Linguist., Univ. Stockholm ...