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B R Gerratt

Publications and source records attributed to B R Gerratt.

48 records · Page 3Linked to original sources
PubMed1987

Aphasic performance on a lexical decision task: multiple meanings and word frequency.

The lexical access of words varying in the number of meanings and frequency of occurrence was examined in fluent and nonfluent aphasic individuals and a control group of non-brain-damaged adults, using a lexical decision task. Fluent aphasic subjects performed similarly to nonfluent aphasic and normal subjects, showing that words with a high number of meanings and with a high frequency of occurrence were recognized as real words faster than words with few meanings or a low frequency of occurrence. While previous research has demonstrated that the number of meanings associated with a word exerts a powerful influence on the internal lexicon of normals, the results of this study suggest that brain damage resulting in aphasia does not disrupt this semantic organization.

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PubMed1987

Laryngeal modeling: theoretical, in vitro, in vivo.

Because the larynx is situated anatomically in an area which is difficult to measure and visualize, theoretical, in vitro, and in vivo models are used in laryngeal research. Vocal fold vibration was studied in anesthetized dogs, while electrically stimulating independently the superior and recurrent laryngeal nerves under conditions of constant airflow. Photoglottographic (PGG), electroglottographic (EGG), and subglottic pressure signals were obtained while stroboscopically photographing the larynx. Specific points along PGG, EGG, and subglottic pressure waveforms were correlated with laryngeal events which occurred during vibration. The canine larynx, in an experimentally produced phonatory mode, vibrates in a two mass (upper and lower margin) system and appears comparable to modal human voice production. The recorded glottographic waveforms from experimentally produced phonation in the canine are similar to signals recorded from humans. However, observed differences can be related to anatomic differences.

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PubMed1984

Speech abnormalities in tardive dyskinesia.

Twelve outpatients with tardive dyskinesia underwent speech evaluation by trained listeners who analyzed oral reading and vowel production for deviation in multiple speech dimensions. In the six patients with speech abnormalities, temporal organization and voice production dimensions were the most severely deviant and were highly related to the overall intelligibility and bizarre quality of speech. Deviations in articulation were less prominent. Abnormal involuntary movement scale ratings of the trunk in these patients were significantly greater than in the patients without speech impairment, although the lingual-facial-buccal and total body scores were similar between the two groups.

Adult↗
PubMed1984

Cinegraphic observations of laryngeal function in Parkinson's disease.

Thirty-two unselected male patients with Parkinson's disease were examined by telescopic cinelaryngoscopy. Correlation of vocal abnormality and general neurologic symptoms with the laryngoscopic examination leads to the conclusion that the phonatory abnormalities noted in Parkinson's disease are related to rigidity in the phonatory posture of the larynx. The described dysfunctions correlated with the symmetry of trunk and limb rigidity in 100% of the patients.

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PubMed1983

Formant frequency fluctuation as an index of motor steadiness in the vocal tract.

Involuntary movement of the articulatory structures can interfere with the accurate placement of the articulators during consonant production and may also result in distortion of vowel quality. An acoustic method was used to assess motor steadiness in the vocal tract musculature superior to the glottis during vowel production by five subjects with abnormal involuntary orofacial movements associated with tardive dyskinesia and 10 normal subjects. A linear predictive coding technique of spectral analysis yielded formant frequencies from the sustained productions of /a/. Based on the premise that changes in vocal tract configuration can be measured as changes in formant frequency, the sequential segment-to-segment fluctuations of the second formant frequency of these vowel samples were computed and used as an index of motor steadiness. Results showed that formant frequency fluctuation measures for four of the five tardive dyskinetic patients were substantially larger than those of the normal subjects, indicating a reduction of motor steadiness in these four subjects. Factors influencing the validity of this procedure and implications for its use are discussed.

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PubMed1983

An acoustic analysis of the effects of surgical therapy on voice quality.

An automated computer system was used to measure changes in vocal quality resulting from laryngeal surgery. Five acoustic parameters were computed and seven listeners made judgments on vowel samples recorded before and after surgery from 37 patients. Presurgery and postsurgery changes in the five acoustic measures were compared with the perception of change in vocal harshness. A multiple regression analysis showed that four of the five acoustic measures accounted for a large amount of the variance in the judgment of change of voice quality following surgery. The measures may provide a quick and relatively sensitive method that may be clinically useful in measuring change in vocal quality.

Adult↗
PubMedDate not supplied

Effect of superior laryngeal nerve stimulation on phonation in an in vivo canine model.

We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in Fo, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle.

Animals↗
PubMedDate not supplied

Synchronizing videostroboscopic images of human laryngeal vibration with physiological signals.

PURPOSE: This report describes a new system that permits the precise correlation of videostroboscopic images with corresponding physiological measures, such as glottography and subglottic pressure. METHOD: A healthy volunteer had unilateral vocal cord paralysis induced by infiltrating local anesthesia into the recurrent and superior laryngeal nerve. Vocal-fold vibrations were monitored by photoglottography (PGG) and electroglottography (EGG). Analog signals from the EGG and PGG were synchronized with the video and correlated. RESULTS: The method described permits images to be sampled throughout sustained phonation. This technique allows study of events during glottic vibration. Results obtained have been in close agreement with previous studies that correlate the vocal-fold morphology to glottographic signal using other methods. This technique is inexpensive in comparison with high-speed filming. The main disadvantage of this method is related to the limitations of stroboscopy.

Adult↗
PubMedDate not supplied

Laryngeal configuration associated with glottography.

This report describes a method for testing and confirming the relationship of glottography to the vibratory movements of the vocal folds. According to this method, vocal fold movement is monitored by photoglottography (PGG) and electroglottography (EGG) as photographs are taken using a 80-microsecond flash provided by a laryngostroboscope. The flash is recorded as an impulse on the PGG waveform, indicating the location on the glottographic signals of the corresponding single frame photograph. We then present a test case, in which various vocal fold configurations are documented, demonstrating that the timing of glottal events can be correlated to glottographic signals by this method.

Adult↗
PubMedDate not supplied

Glottographic measurement of vocal dysfunction. A preliminary report.

Objective measurement of vocal function is important in evaluating phonatory disorders, planning treatment, and documenting the effects of therapy. Glottographic measurement, ie, measures that describe glottal movement, can be performed and analyzed relatively easily, and can be related to the pathophysiology of vocal dysfunction. In our clinic, simultaneous recording of acoustic, photoglottographic and electroglottographic signals is being used in the evaluation of patients with voice disorders associated with neurologic impairments. Our experience with these measures indicates that they may provide detailed information about the vibratory patterns of the vocal folds, which appears to differentiate some phonatory characteristics among patients with differing types of disorders.

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