Dale Evan Metz

An acoustical analysis of stutterer's speech prior to and at the termination of speech therapy

Abstract The speech of nine adult stutterers was analyzed acoustically prior to and at the termination of a modified Van Riperian procedure to determine if therapy produced discernable changes in their post-therapy fluent speech. The findings indicate that stuttering frequency decreased significantly and reading rate decreased by a statistically insignificant amount during the course of therapy. Vowel duration and the occurrence of voicing during the stop consonant production increased significantly. These findings support the hypothesis that stuttering therapy can affect more than the fluency and rate characteristics of the stutterers posttherapy speech.

Articulatory dimensions of hearing-impaired speakers' intelligibility: evidence from a time-related aerodynamic, acoustic, and electroglottographic study.

Regression and principal components analyses were employed to study the relationship between 30 aerodynamic speech parameters and the speech intelligibility of 40 severely to profoundly hearing-impaired speakers. Regression analysis on the original 30 aerodynamic variables revealed that speech intelligibility was predicted by a cognate-pair voice onset-time difference measure and a measure of the stability of the volume-velocity rise time. Principal components analysis of the 30 independent variables derived seven factors that accounted for 84.3% of the variance in the original 30 parameters. Subsequent regression analysis using the seven factors as predictor variables revealed four factors with independent relationships to speech intelligibility. These included a factor that reflected cognate-pair voice onset-time distinctions, a factor that reflected cognate-pair peak volume-velocity distinctions, and two other factors, which reflected production stability of temporal distinctions between cognate pair members.

A distinctive-features approach to the remediation of voicing errors produced by hearing-impaired adults.

An articulation training procedure based on the clinical extension of distinctive-feature theory was used in an attempt to correct selected voicing errors exhibited by eight hearing-impaired adults. The results indicate that the production of the [+ voice] feature was mastered by all subjects in the phonetic context where it was trained, but generalization of the [+ voice] feature-usage rule was not achieved by the subjects. The findings are discussed relative to the use of feature-training procedures with hearing-impaired adults.

The use of artificial neural networks to estimate speech intelligibility from acoustic variables: A preliminary analysis

Previous research has used regression analysis to attempt to predict the intelligibility of hearing-impaired speakers from acoustic speech parameters. Improvement of prediction may be achieved by the use of computerized artificial neural networks to process mathematically the acoustic input variables as part of the intelligibility process. A preliminary scheme for estimating speech intelligibility from acoustic parameters using a neural network is outlined and preliminary data illustrate its use.

Changes in stutterers' fundamental frequency contours following therapy

Abstract The fundamental frequency (FO) declination observed during the first 50 msec in vowels that follow voiced stop-consonant productions was examined in the fluent speech of 53 stutterers before and at the termination of an intensive therapy program. Results indicate that therapy has no effect on the FO declination patterns. These results are interpreted with respect to research findings regarding fluent and disfluent speech productions of stutterers.

A New Optical/Lighting System For High Speed Laryngeal Cinematography

Abnormal laryngeal function during speech produced by many profoundly deaf students attending the National Technical Institute for the Deaf is indicated by acoustical and perceptual measures. To assist in objectifying the diagnosis and treatment of these vocal disorders, a physiological assessment of laryngeal activity is warranted. High speed laryngeal photography was selected as a principle tool for this assessment because of the very rapid vibratory period of the vocal cords. To illuminate the larynx for film speeds of up to 6,000 frames per second, a xenon arc light source is coupled with an optical system to project a high intensity light beam on the vocal folds. The projected beam is filtered to reduce infra-red and ultra-violet radiation. Light is projected paraxial to the camera lens to intersect on a laryngeal mirror positioned in the oropharynx of the subject. Methods of synchronizing the high speed film with additional acoustic and physiologic measures will be discussed.