A Comparison of Two Methods of Formant Frequency Estimation for High-Pitched Voices

This study sought to compare formant frequencies estimated from natural phonation to those estimated using two methods of artificial laryngeal stimulation: (1) stimulation of the vocal tract using an artificial larynx placed on the neck and (2) stimulation of the vocal tract using an artificial larynx with an attached tube placed in the oral cavity. Twenty males between the ages of 18 and 45 performed the following three tasks on the vowels /a/ and /i/: (1) 4 seconds of sustained vowel, (2) 2 seconds of sustained vowel followed by 2 seconds of artificial phonation via a neck placement, and (3) 4 seconds of sustained vowel, the last two of which were accompanied by artificial phonation via an oral placement. Frequencies for formants 1-4 were measured for each task at second 1 and second 3 using linear predictive coding. These measures were compared across second 1 and second 3, as well as across all three tasks. Neither of the methods of artificial laryngeal stimulation tested in this study yielded formant frequency estimates that consistently agreed with those obtained from natural phonation for both vowels and all formants. However, when estimating mean formant frequency data for samples of large N, each of the methods agreed with mean estimations obtained from natural phonation for specific vowels and formants. The greatest agreement was found for a neck placement of the artificial larynx on the vowel /a/.     

Laryngeal and Vocal Changes During Vagus Nerve Stimulation in Epileptic Patients

Left vagus nerve stimulation (VNS) by means of an implanted electrode has proven to reduce seizure frequency in epileptic patients with medically refractory seizures. This technique is now widely applied over the world. Voice changes appear to be one of the major side effects. The morphodynamic changes in the larynx and the acoustic impacts have been analyzed in detail in 7 implanted patients. Basic vagus stimulation is well tolerated. Extra stimulation induces an adductory spasm of either the ipsilateral vocal fold or the vestibular fold. The result, when the patient phonates, consists of a slight increase of F0 as well as a moderate increase of random period perturbation, but there is no evidence for the occurrence of "bifurcations." Further, as the glottic closure remains sufficient, there is no increase in turbulent noise. The lack of increase in turbulent noise and the lack of "bifurcations" appears to clearly differentiate a spasmodic contraction of the vocal cord from a unilateral vocal fold paralysis.     

Mid-Basal-to-Ceiling Versus Mid-Ceiling-to-Basal Elicitation of Maximum Phonational Frequency Range

The purpose of this study was to investigate if there was an effect of task on the determination of maximum phonational frequency range (MPFR). Two tasks commonly used to elicit MPFR in clinical voice evaluations were compared. Normal adult females (n = 30) were examined. No statistically significant effect of task was found. Both tasks (mid-basal-to-ceiling and mid-ceiling-to-basal) were found to have a high positive correlation (0.89). Implications of the use on one task to determine maximum phonational frequency range are discussed, as is the possibility of a task effect on determination of other voice parameters.     

The Voice and Its Care: Survey Findings From Actors'' Perspectives

There is a need for research that would determine how the speech-language-voice pathologist could best be of service to actors who are experiencing vocal dysfunction or in furnishing preventive educational information. A questionnaire investigating interest and knowledge levels of vocal function and dysfunction was distributed to 543 subjects from the Pacific Northwest and British Columbia. A total of 345 questionnaires, including those completed by 79 professional actors, 73 amateur actors, 124 acting students, and 69 controls, were analyzed. Professional actors and amateur actors indicated the highest levels of interest in gaining further knowledge regarding the role of the speech-language pathologist (SLP) and the voice and vocal hygiene. Professional actors and amateur actors also reported higher perceived knowledge levels than the other groups in these areas, although very few claimed to have a thorough knowledge in the areas under investigation. Professional actors answered more knowledge-based questions correctly than amateur actors, acting students, and controls in the areas regarding the role of the SLP and voice and vocal hygiene. However, the professional actors' scores were not significantly higher than amateur actors in either area and were only significantly higher than acting students on the vocal hygiene items. Implications for a preventive approach to vocal health are discussed.