Measurements of the aero-acoustic properties of the vocal folds and vocal tract by broad and narrow band probes during phonation into controlled acoustic loads

Abstract

The aeroacoustic properties of the vocal folds and tract are difficult to measure directly. Here, they were measured using broad- and narrow-band excitation at the mouth during phonation into various acoustic loads, including a non-resonant load provided by an acoustically infinite waveguide with cross section comparable with that of the tract. The tract is treated as a duct terminated by the larynx. Mechanical properties of the walls and terminations were determined using a microphone array [Dickens et al. (2007)]. The vocal fold response was monitored with an electroglottograph and wall motion was measured electromechanically. The impedance spectra show negative resistance bands at frequencies near those of phonation, consistent with regeneration at the folds. The walls give inertances consistent with thicknesses of order 1 cm and compliances consistent with distributed stiffnesses of about 100 kN/m3 [Hanna et al. (2012)]. The duct resonant properties are consistent with losses several times higher than the viscothermal losses at smooth rigid walls. Dickens et al., J. Acoust. Soc. Am. 121, 1471–1481 (2007). Hanna et al., in Proceedings of the Australian Acoustical Society Conference (2012).