The effects of orthognathic surgery on speech production.

Speech characteristics of 20 patients who underwent orthognathic surgery for correction of various skeletal defects were studied before surgical treatment and at periodic intervals postoperatively. Patients completed questionnaires that focused on their perceptions of appearance and oral function after orthognathic surgery. Approximately 60% of the patients demonstrated preoperative articulation errors. These were classified as mild because they did not interfere with the ability to be understood. Periodic testing indicated positive changes in articulation for a majority of those who had exhibited preoperative errors. None of the subjects experienced postoperative deterioration in their articulation. The subjects' perceptions of their individual operations were positive on all variables assessed.

Speech production before and after orthognathic surgery: a review.

A review of investigations in which speech production has been studied before and after orthognathic surgery indicates that many subjects demonstrate preoperative articulation errors. The error type most frequently identified was of the distortion variety, which suggests that misarticulating speakers were attempting to produce the sounds but that in most cases the sounds were phonetically incorrect. The /s/ speech sound and the sibilant class in general, of which /s/ is a member, were often found defective in the subjects' speech. Not all speakers had preoperative articulation errors, which suggests the possibility of compensatory articulation patterns. The literature indicates that some persons with certain occlusal and dental conditions do compensate for structural aberrations. Finally, the vast majority of subjects with preoperative misarticulations eliminated or reduced their errors following orthognathic surgery. In the case of speech behavior, it can be stated that surgical alterations in form brought about positive changes in function.

Functional regulator therapy for cleft palate patients.

Nine cleft lip and palate children exhibiting collapse of maxillary segments and cross-bite were treated orthodontically with the functional regulator (FR) for periods ranging from 6 to 18 months. The purpose of this investigation was to evaluate quantitatively treatment of cleft palate patients with the functional regulator and to evaluate the effect of the appliance on their speech. Cleft palate patients typically have speech, nose, and lip defects which make patient cooperation and appliance acceptance more difficult. However, patient cooperation was considered good with an average mean of 12.7 hours per day of appliance wear and a range of 5.6 to 18.2 hours. Change in interimplant dimension was measured on frontal radiographs, and dental changes were measured of serial dental casts. The resulting data indicated no significant change in maxillary width or cross-bite relationship. The functional regulator was not clinically useful in this sample when the treatment objective was primary expansion of collapsed maxillary segments in the cleft palate patient. Good speech-production skills prior to treatment will minimize the adverse effect that the FR has on speech intelligibility. A significant amount of accommodation to the appliance occurs within 1 week after insertion, but maximum improvement in speech intelligibility occurs with full-time wear of the appliance for as many hours per day as possible.

Developmental apraxia: diagnostic considerations.

This study compares the performance of developmentally apraxic children with that of children who have functional articulation disorders on a battery of diagnostic tests. Based on preliminary data, tests which assess auditory attention, auditory discrimination, auditory memory, oral-tactile feedback, and isolated and sequenced volitional oral movements appear to be useful in a differential diagnosis of articulatory defective children and, thus, warrant further study. Implications of these findings are discussed.

The perception of temporally segmented vowels and consonant-vowel syllables.

The minimum initial-portion durations required by listeners for the correct identification of spoken isolated vowels and consonant-vowel (CV) syllables were determined. Eight vowels [see text] and 64 CVs comprised of each of eight consonants [see text] in combination with each of the eight vowels were used. Segments consisted of the initial 10 to 150 milliseconds of each stimulus in 10-msec steps. The major findings were (1) clues for better than change correct identification of tongue advancement and tongue height values for isolated vowels occur within the first 10 msec of the stimuli whereas approximately 30 msec of the stimuli are needed for the tense-lax feature to reach threshold, (2) clues for better than chance correct identification of place of articulation for the stop consonants are found within the initial 10 msec of the CVs whereas approximately 22 msec are needed for the voicing threshold to reach threshold, and (3) the threshold of voicing increases from front to back place of articulation for the stop consonants. The implications of the findings are discussed.

Perception of vowel features in temporally-segmented noise portions of stop-consonant CV syllables.

The ability of listeners to identify vowel features, given only segments of the aperiodic portion of CVs, was investigated. Segments of the aperiodic portions of stop consonant CVs, increasing in duration in 10-msec steps from onset, were identified by 18 listeners. The responses were analyzed for the correct identification of vowel features. Coarticulatory effects of the vowel on the aperiodic portion were found to (1) occur early in the aperiodic portion, (2) vary with consonant and vowel, and (3) vary with vowel feature. In general, however, tongue advancement for the vowel was identified correctly most often, tongue height next most often, and the tense versus lax distinction least often. For some CVs, sufficient clues for above chance level of identification of a feature were present during the shortest segments of the aperiodic portion. The findings lend support to the point-of-view that listeners may be able to narrow the choice of the vowel in an unvoiced-stop-consonant CV to a small number of alternatives prior to the beginning of voicing.

Perception of temporal order of vowels and consonant-vowel syllables.

Recent findings indicate that the presence of formant transitions aids the perception of the order of stimuli in repeating sequences of vowels or consonant-vowel (CV) syllables. In this study, 12 listeners reported the perceived order of four vowels or CVs in repeating sequences. Stimuli ranged in duration from 75 to 300 msec in 25-msec steps. Four stimulus sequences were used (1) varying vowels (Vv), (2) CVs with varying consonants but a constant vowel (CvVc), (3) CVs with a constant consonant but varying vowels (CcVv), (4) CVs with consonants and vowels varying (CvVv). Percentage of correct identification of order was significantly higher and mean threshold duration significantly lower for the CvVv and CvVc conditions than for the Vv condition. Mean number of sequences per response was significantly smaller for the CvVv condition than for the other conditions. Threshold durations ranged from 100 msec for the CvVv sequences to 135 msec for the Vv sequences. Ordering performance was nearly perfect for stimulus durations of about 225 to 250 msec. The results support the hypothesis that as stimuli in repeating sequences more closely resemble connected speech, listeners can more easily correctly identify the order of the stimuli.