Visual observations of glottic activity during didgeridoo performance

Australian didgeridoo is a reed-less hollow conically shape wooden tubular wind instrument typically measuring up to 150 cm in length, with distal and proximal diameters ranging from 150 to 30 mm. This tube allows a player to produce only a narrow variety of sound and sounds effects because it is coupled directly to the player's vocal tract. The typical frequency of the tube typically called the drone, is approximately within 60 to 100 Hz range. This tone generation modulated by lip vibration is supported by circular breathing, allowing for an uninterrupted (indefinite) length of sound generation. Inhalation introduces sound pulsation, while specific tonal effects can be consciously created by manipulation of the player's lips and/or the vocal tract, including conscious phonation using vocal folds vibration, all used to enrich both the sound and the artistic meaning of the played sequence. Though the results of the research on the acoustics of this instrument are often reported in the literature, physiologic data regarding vocal tract configurations, and especially on the behavior of the vocal folds in regulation of ventilation and in phonation, remain less than underreported. The data presented here comprises (as far as we were able to determine) the first ever physiologic account of vocal fold activity in a didgeridoo player observed with help of trans-nasal endoscopy. Our focus was to reveal the work of t