Estudo dos ajustes laríngeos e supralaríngeos no canto dos contratenores: dados fibronasolaringoscópicos, vídeo-radioscópicos, eletroglotográficos e acústicos

Abstract

Objective: To investigate the laryngeal and supralaryngeal adjustments of the countertenor singing voice in a musical context, trying to elucidate the voice production mechanism and to identify the relationship between these adjustments and the acoustical characteristics of the voice source and of the filter in falsetto. Methods: four countertenors were evaluated with videofiberscopy, video-radioscopy, electroglottography, and acoustic analysis. Four types of tasks (fast melodic movement, descending scales, leap interval and crescendo in a sustained note) were performed by the participants, all tasks being inserted in an usual musical context.The videos were analyzed, information concerning laryngeal adjustments and supralaryngeal gestures was obtained, and these data were compared with measures taken from the electroglottographic (closed quotient) and acoustic analysis recordings (singers formant). Results: in the four tasks, the results were distinct. The laryngeal and supralaryngeal behavior evidenced lowering of the larynx in the fast melodic movement, descending scale and crescendo tasks, and discrete rise in the leap interval tasks. The predominance of larynx lowering occurred up to D5 (587 Hz), larynx rising being observed in F#5 (740 Hz). The soft palate remained closed and high, the tongue rose with little variation in the anteroposterior axis and the lips were protruded during most part of the emissions. The closed quotient varied from 42% to 50%, whereas the singers formant was present in all tasks, but not for all the participants, being also less present in the task of octave leap (F#4 F#5). Conclusions: The countertenors always used the technique of larynx lowering that predominantly occurred in almost all situations of the recordings. Small lateral constrictions of the lower pharynx were observed when they emitted notes above D5 (587 Hz). The closed uotient varied from 42% to 50%, on average, but it ranged from 20% (in emissions in the lower range) to a 75% peak (in leap interval emissionsnext to the top of the tessitura). The singers formant was commonly present, with high amplitude levels peaks in the range of 2750-3250 Hz. The countertenors used mechanisms for F0-F1 tuning, such as jaw lowering, in regions where F0 was equal or larger than F1, resulting in greater acoustic energy transference to the vocal tract, due the high value of the supraglottic impedance.