A physiological and acoustic study on voiced bilabial fricative /β:/ as a vocal exercise

The voiced bilabial fricative /β:/ has been used as a vocal exercise. The present study investigated the effects of the exercise on voice production and voice source. This study compared vowel phonation on the syllable /a:p/ with the production of the exercise and vowel phonation before and immediately after the exercise. The methods were (a) dual-channel electroglottography, from which the vertical laryngeal position was derived, (b) electromyography using surface electrodes, and (c) inverse filtering of the acoustic signal to obtain an estimate of the voice source. In the production of /β:/ as compared with vowel phonation in most of the cases, the vertical laryngeal position seemed to be higher, the muscular activity of the larynx lower, and the slope of the voice source spectrum steeper. In vowel phonation after the exercise, the muscular activity seemed to be lower in most cases, although the voice source remained unchanged. This seems to indicate improved vocal economy.     

Technique of percutaneous EMG-guided botulinum toxin injection of the larynx for spasmodic dystonia

Percutaneous electromyography (EMG)-guided technique of botulinum toxin (BT) injection of the larynx evolved from similar techniques for extraocular muscle injection in strabismus, as well as from experience with diagnostic laryngeal EMG. This technique permits rapid accurate injection of BT into the laryngeal muscles. Although usually injected into the thyroarytenoid muscle, BT can also be directed to the posterior cricoarytenoid and cricothyroid muscles. Complications are minimal and of short duration.     

A study on the mechanism of functional dysphonia

A total of 333 patients with a diagnosis of functional dysphonia were studied by both laryngeal electromyography (EMG) and spectral analysis. EMG and acoustic analysis revealed that some patients with so-called functional dysphonia diagnosed by physical examination alone in fact suffered from a variable degree of laryngeal nerve paralysis. Laryngeal EMG plays an important role in determining whether patients with a diagnosis of functional dysphonia have organic disease of the laryngeal nerves.     

External laryngeal frame function in voice production revisited: A review

Reserch indicates significant contribution of extrinsic laryngeal mechanisms to voice production. This article reviews the major theories of the role of the external laryngeal factors in voice production and relevant experimental data. The review suggests that partly neglected external factors and possibly even misinterpretation of some of the recently documented individual variation in physiological data may have unnecessarily complicated the issues pertaining to the interplay between the physiological mechanisms of the larynx. The implications of contemporary findings and documentation in the modeling of the extrinsic factors are discussed and a synthesis of empirical data into two simple models of the extrinsic forces of pitch control is presented. Also suggested by the review, a basic principle, probably underlying the laryngeal control of phonation, is put forward.     

Comparison of direct and indirect calculations of laryngeal airway resistance in connected speech

Direct measures of subglottal pressure obtained through a tracheal puncture were used to calculate laryngeal airway resistance. Six subjects completed tasks including syllable trains and more natural speech samples produced at three loudness levels. Direct calculations of natural speech resistance values were compared with indirect estimates obtained during syllable train production. The degree of correspondence between direct and indirect calculations varied by subject. Overall, the smallest relative errors among calculations occurred for syllable trains, with higher relative errors for the monologue and sentence. For loudness conditions, the smallest and largest relative errors occurred for soft and loud productions, respectively. The clinical utility of indirect estimation is questioned and suggestions for improving its validity are provided.     

Endolaryngeal changes during high-intensity phonation videolaryngoscopic observations

Using a five-part vocal figure and standard fiberoptic techniques, we have analyzed the laryngeal functions of a group of professional singers and have made five observations occurring during high-intensity phonation that contradict the accepted physiologic functioning of the larynx. We have analyzed these contradictions as they relate to the three endolaryngeal sphincters; this was accomplished by the development of a four-component vocal protocol to examine the changes in these laryngeal structures and the degree of independent control of each of these structures possible in this group of specialized subjects. We have attempted to explain our findings based on available data relating to the functions of the intrinsic and extrinsic laryngeal musculature (including the cricothyroideus muscle) and the neurologic mechanisms involved. Finally, we discuss this data as it relates to current vocal training.