Regulatory Mechanism of Voice Intensity Variation

Abstract

The relationship between the voice intensity (sound pressure level), the subglottic pressure, the air flow rate, and the glottal resistance was investigated. Simultaneous recordings were made of the sound pressure level of voice, the subglottic pressure, the flow rate, and the volume of air utilized during phonation. The glottal resistance, the subglottic power, and the efficiency of voice were calculated from the data. It was found that on very low frequency phonation the flow rate remained almost unchanged or even slightly decreased with the increase in voice intensity while the glottal resistance showed a tendency to augment with increased voice intensity. In contrast to this, the flow rate on high frequency phonation was found to increase greatly, while the glottal resistance remained almost unchanged as the voice intensity increased. On the basis of the data it was concluded that at very low pitches, the glottal resistance is dominant in controlling intensity (laryngeal control), becoming less so as the pitch is raised, until at extremely high pitch the intensity is controlled almost entirely by the flow rate (expiratory muscle control).

Restraining mechanisms in regulating glottal closure during phonation

“…3(d)]. This confirms Isshiki's (1964) hypothesis that control of vocal intensity through adjusting the glottal resistance (presumably through contraction of primarily the CT and TA muscles) is most effective for low-pitch voices for which "the vocal folds are relaxed and the resistance of the glottis is so low that it can be further increased. "…”

“…In humans, such "greater force" or restraining function may be provided by the contraction of the thyroarytenoid (TA) muscle, which stiffens the deep body layer of the vocal fold, and the cricothyroid (CT) muscle, which stretches and stiffens the vocal fold tension in the anterior-posterior (AP) direction. Although the importance of TA and CT muscle contraction in regulating phonation has long been recognized and has been the subject of numerous studies (e.g., Isshiki, 1964;Hirano et al, 1969;Gay et al, 1972;Tanabe et al, 1972;Ward et al, 1977;Moore et al, 1987;Choi et al, 1993), most of these studies focused on the roles of TA and CT muscle contraction in pitch and vocal loudness control. There has essentially no systematic investigation regarding the possible restraining effects that contraction of the TA and CT muscles may provide to maintain vocal fold position against the subglottal pressure.…”

“…At large flow rates, the vocal folds were blown wide apart with no vibration. In a study on the laryngeal mechanisms of intensity control, Isshiki (1964Isshiki ( , 1969 argued that, "in order to keep the glottis closed longer, withstanding the increasing pressure below the glottis, greater force to close the glottis is required." In humans, such "greater force" or restraining function may be provided by the contraction of the thyroarytenoid (TA) muscle, which stiffens the deep body layer of the vocal fold, and the cricothyroid (CT) muscle, which stretches and stiffens the vocal fold tension in the anterior-posterior (AP) direction.…”

Variação da intensidade vocal: estudo da vibração das pregas vocais em seres humanos com videoquimografia

“…Isshiki 8,9 , estudando as alterações de intensidade vocal, conclui, em seus estudos, que a resistência glótica é o principal mecanismo envolvido no controle da intensidade vocal em baixas freqüências.…”

Reliable Time to Estimate Subglottal Pressure

“…Many methods have been described to measure P s during sustained phonation, but it remains difficult to ensure accuracy while still maintaining clinical feasibility. Tracheal puncture (1) and insertion of a miniature pressure transducer into the throat through the nose (2, 3 ) measure P s accurately, but the procedures are invasive. Noninvasive methods measuring intraoral pressure have shown promise, but often have unreliable results and high intrasubject variability.…”