Effects on speech of chronic cerebellar stimulation in cerebral palsy.

Chronic cerebellar stimulation of the anterior lobe is undertaken for relief of motor dysfunction in cerebellar palsy, but the effect on speech and vocal ability has been uncertain. The present study evaluated speech before cerebellar stimulation and during the immediate postoperative period in seven severely spastic/athetoid patients with congenital cerebral palsy and one patient with traumatic brain damage. Structured listening tasks were completed in blind fashion by a trained panel of speech pathologists. Group analysis revealed no significant improvement in speech intelligibility or articulatory accuracy after stimulation. With the exception of strain/strangle vocal quality, which improved considerably, vocal characteristics were not affected by cerebellar stimulation. In three of eight patients, however, improvement in certain speech characteristics was noted.

Vocal symptomatology of postoperative dysphonia.

Vocal symptomatology of 24 patients was assessed following the removal of polyps (12 cases) and polypoid degeneration (12 cases). In addition to fundamental frequency, hoarseness type was measured using the spectrographic system developed by Yanagihara which assesses harmonic structure of phonemes relative to noise components. Mean vocal frequency (155Hz) for the polypoid degeneration group was significantly lower than mean vocal frequency for the polyp group (186Hz). There was no difference between the two groups in mean spectrographic hoarseness type. Analysis of data suggested two subgroups of postoperative dysphonia based upon vocal symptomatology: Type A--little or no hoarseness and Type B--severe hoarseness. Neither preoperative nor postoperative conditions of the vocal cords were related to the severity of hoarseness demonstrated by Type B dysphonics. Illustrative cases are presented. One possible explanation for severe postoperative dysphonia is developed.

Acoustic and perceptual comparison of chronic and incipient spastic dysphonia.

Vocal symptoms of patients with chronic and incipient spastic dysphonia were compared on a number of acoustic and perceptual parameters. Patients with incipient spastic dysphonia displayed less severe strain-strangle phonation, effort, rhythm, and stress. Harshness was the only perceptual parameter on which incipient spastic dysphonics were rated higher than chronic spastic dysphonics. Changes in the acoustic measures of laryngealization, harmonic change, mean vowel duration, and duration ratio between stressed and unstressed vowels accompanied changes in listeners' perception of strain-strangle phonation and effort. The variation in acoustic characteristics such as laryngealization and harmonic change as well as normal phonation indicated that both groups were characterized by a variety of phonatory modes.

Perception of dysphonic voice quality by naive listeners.

For clinical assessment as well as student training, there is a need for information pertaining to the perceptual dimensions of dysphonic voice. To this end, 24 naive listeners judged the similarity of 10 female and 10 male vowel samples, selected from within a narrow range of fundamental frequencies. Most of the perceptual variance for both sets of voices was associated with "degree of abnormality" as reflected by perceptual ratings as well as combined acoustic measures, based upon filtered and unfiltered signals. A second perceptual dimension for female voices was associated with high frequency noise as reflected by two acoustic measures: breathiness index (BRI) and a high-frequency power ratio. A second perceptual dimension for male voices was associated with a breathy-overtight continuum as reflected by period deviation (PDdev) and perceptual ratings of breathiness. Results are discussed in terms of perceptual training and the clinical assessment of pathological voices.

Diphthong changes in style shifting from Southern English to Standard American English.

This study was undertaken to identify the acoustic correlates of the diphthongs /aI/ and /contains as a subset I/ in individuals who were trained to "style shift" between Standard American English (SAE) and Southern English (SE). The diphthongs were produced by four individuals from the coastal southern dialect region who were selected from among those who had successfully completed an accent-reduction program. Results showed that diphthongs used in SE were shorter and had less noticeable transitional elements than those in SAE. The difference was more apparent for /aI/ than /contains as a subset I/. There were no instances in which a diphthong was completely replaced by a vowel in SE. Findings indicate that acoustic analysis may be a useful tool in identifying dialectal elements, particularly for those individuals who are learning to style shift.

Speech changes in Parkinson's disease during treatment with L-dopa.

The speech of 17 Parkinsonian patients was evaluated before and after the administration of L-DOPA therapy. A significant difference was demonstrated after treatment for voice quality, articulation, and pitch variation, but not for rate of speech. Amount of speech improvement correlated significantly with amount of physical improvement. Although age and duration of disease may exert some influence on speech change, the results suggest that these factors do not reliably predict the response. After 4 years of L-DOPA therapy, three out of four patients demonstrated additional improvement or the same degree of speech improvement.

Effects of perceptual training based upon synthesized voice signals.

28 undergraduate students participated in a perceptual voice experiment to assess the effects of training utilizing synthesized voice signals. An instructional strategy based upon synthesized examples of a three-part classification system: "breathy," "rough," and "hoarse," was employed. Training samples were synthesized with varying amounts of jitter (cycle-to-cycle deviation in pitch period) and harmonic-to-noise ratios to represent these qualities. Before training, listeners categorized 60 pathological voices into "breathy," "rough," and "hoarse," largely on the basis of fundamental frequency. After training, categorizations were influenced by harmonic-to-noise ratios as well as fundamental frequency, suggesting that listeners were more aware of spectral differences in pathological voices associated with commonly occurring laryngeal conditions. 40% of the pathological voice samples remained unclassified following training.

Consonant-vowel interaction in an unusual phonological system.

This paper presents information regarding the interactive effects of consonants and vowels in a disordered phonological system. Labial and labiodental consonants were produced as alveolar consonants before front vowels and labial consonants before back vowels. Motivation for the sound change is discussed in terms of assimilation and labial constraints. Implications for therapeutic intervention are discussed.

Prediction of vocal severity within and across voice types.

Fifty-one subjects representing diverse laryngeal etiologies recorded /a/ and /i/ to provide a study sample of 102 vowel sounds. Listeners categorized each vowel on the basis of four voice types (normal, breathy, hoarse, unclassified) and evaluated the degree of vocal abnormality on a 7-point scale. In addition to spectrographic noise (SN) classification, several acoustic measures based on period variability were entered into a multiple regression analysis for the prediction of vocal severity across and within voice types. In general, spectrographic noise and curvilinear derivatives of the period standard deviation (PSD) provided the best predictions of disorder severity. Different variables were the major predictors for different voice types. Several variables used in previous studies were inefficient as predictors of severity.

Use of a high-risk register in newborn hearing screening.

High-risk newborns were routinely screened for hearing loss by observing their behavioral responses to a 3000-Hz warbled tone at 90 or 100 dB SPL. Infants were identified as high risk if they presented any of the conditions listed by the Joint Committee on Infant Hearing Screening or if they were placed in the special care or intensive care sections of the newborn nursery. During the program's first 12 months, 17% of the total newborn population were included in the screening, and 7% of those screened failed to respond. Approximately half of the infants who failed the screening returned for follow-up testing. No hearing loss has been identified among these infants. Special steps have been required to improve the screening's effectiveness.

Spectrographic comparison of two types of spastic dysphonia.

A spectrographic comparison of the voices of two patients with spastic dysphonia demonstrated differences in vocal characteristics. The voice of one patient was characterized by intermittent breathiness which appeared spectrographically as a breakdown in formant structure or as the addition of fricative fill superimposed upon resonance bars. The voice of the second patient was characterized by strain-strangle phonation which appeared spectrographically as widely and irregularly spaced vertical striations. The contrasting vocal characteristics of the two patients are compatible with the viewpoint that there may be two types of spastic dysphonia.

Acoustic and perceptual measurements of roughness influencing judgments of pitch.

Listeners matched the pitch of 36 clear to severely dysphonic vowels to the frequency of pure tones produced by a signal generator. Mean difference scores on pitch match correlated-.56 with jitter, -51 with jitter ratio, -.57 with spectrographic noise classifications, and -.64 with vocal roughness. Moderately to severely dysphonic vowels received significantly lower pitch match values than clear to mildly dysphonic vowels. Findings suggest that the effect of vocal roughness on pitch should be considered by the clinician who makes use of perceptual judgments.

Long-term effects on speech of chronic cerebellar stimulation in cerebral palsy.

Chronic cerebellar stimulation (CCS) of the anterior lobe is undertaken for relief or motor dysfunction in cerebral palsy, but the long-term effect on speech and voice has been uncertain. The present study evaluated speech before cerebellar stimulation and between one year and two years, seven months following stimulation in nine patients with congenital cerebral palsy and one patient with traumatic brain damage. Severity of dysarthria was not significantly altered as assessed by a panel of listeners. No patient demonstrated deteriorations in speech. Only two of the 10 patients showed small positive changes in the majority of parameters evaluated including rate, articulation, and voice.

Intonation and fundamental frequency in male-to-female transsexuals.

Twenty speakers, diagnosed as male-to-female transsexuals, produced conversational recordings of speech and voice. The samples were submitted to perceptual evaluations and to acoustic analysis by means of a Visi-Pitch, Apple IIe microcomputer system. Transsexuals categorized as having female voices had higher fundamental frequencies (fo), less extensive downward intonations, a higher percentage of upward intonations and downward shifts, and a smaller percentage of level intonations and level shifts than transsexuals categorized as having male voices. The lowest average fo identified as belonging to a female speaker was 155 Hz. Higher (more feminine) ratings on the masculinity-femininity dimension correlated with fo (r = .89), percentage of level shifts (r = -.67), percentage of downward shifts (r = .50), percentage of level intonations (r = -.43), and percentage of upward intonations (r = .40). Findings are discussed in terms of the relative perceptual salience of average fundamental frequency and patterns of intonation for female voice quality.