A methodological study of hemilaryngeal phonation

Abstract

An excised hemilarynx setup was developed. The phonatory characteristics of nine excised canine larynges were examined. The left vocal fold of each larynx was then removed and substituted with a vertical plexiglass plate. The larynges were phonated again. Recordings were made of phonation threshold pressure, sound pressure level, average glottal flow, fundamental frequency, and amplitude of vocal fold vibration as observed with a video stroboscope. Measurements were made over a range of subglottal pressures. For the hemilarynx, simultaneous recordings of intraglottal pressure and vocal fold contact area were also made. It was found that amplitude and frequency of vocal fold vibration of the hemilarynx, as well as rates of change of amplitude and frequency as a function of subglottal pressure, were similar to those of the full larynx. Also similar were phonation threshold pressures and ranges of subglottal pressure over which the larynges phonated. The average airflow of the hemilarynx was approximately half that of the full larynx, and the sound pressure level, under similar conditions, was one fourth (about 6 dB less) in the hemilarynx.

An overview of the physiology, physics and modeling of the sound source for vowels.

“…This wave is typically referred to as the mucosal wave or vertical phase difference and is most clearly observed in the coronal plane. Vocal fold motion in this plane (along the axis of airflow) was first viewed with X-ray techniques [5] and more recently with observations of excised hemilaryngeal vibration using videostroboscopy [6] and high-speed video [7]. It is also noteworthy that Chiba and Kajiyama [8] used a stroboscopic technique to obtain motion pictures of the vocal folds during vibration.…”

Verification of two minimally invasive methods for the estimation of the contact pressure in human vocal folds during phonation

“…The oscillation amplitude of the vocal folds may be estimated through the postprocessing of digital image data. Jiang and Titze (1993) followed this approach to compare the flow-induced response of hemilarynges and full larynges. Comparable vibration amplitudes and fundamental frequencies were found over a range of subglottal pressures.…”

Excised larynx experimentation: history, current developments, and prospects for bioacoustic research

“…Amongst others, work has been carried out with a strong inclination towards fluid dynamics. This includes studies investigating (a) pressure-flow relationships (Alipour et al, 1997;Hottinger et al, 2007); (b) glottal resistance Alipour and Jaiswal, 2009) and glottal efficiency (Titze, 1988); (c) velocity fields within the glottis using particle imaging velocimetry (which in simple terms corresponds to turbulence analysis) ; (d) the dependency of f o on subglottal pressure (Solomon et al, 1994;Alipour and Scherer, 2007;Alipour and Jaiswal, 2008); and (e) the relationship between subglottal pressure and non-linear dynamics of laryngeal voice production (defining the phonation instability pressure, PIP) (Jiang and Titze, 1993;Jiang et al, 2003). Further research emphasis has been directed towards connecting vocal fold motion and geometry with the acoustic signal produced: this includes, amongst others, studies investigating (a) nonlinear dynamics in relation to glottal geometry (vocal fold adduction and/or elongation) (Berry et al, 1996;Jiang et al, 2003) and vocal fold asymmetry (Giovanni et al, 1999); (b) the importance of tissue properties on phonatory characteristics (Chan and Titze, 1999;Alipour et al, 2011); (c) mucosal wave propagation on the vocal folds (Kusuyama et al, 2001;Jiang et al, 2008); and (d) the mechanical forces applying on the vocal folds during phonation (Verdolini et al, 1998;Jiang et al, 2001b;Bakhshaee et al, 2013).…”

“…This biophysical approach has often also proved useful for physical modeling of voice production (Titze, 1984(Titze, , 1989Alipour-Haghighi and Titze, 1991;Tokuda et al, 2007). In line with this view, hemi-larynx setups have been designed, where the larynx is cut medially, with one half of the larynx removed, and where vocal fold oscillation is recorded both from the sagittal plane and from above (Baer, 1981;Durham et al, 1987;Jiang and Titze, 1993)-see Herbst et al (2017) for a review and video instructions. Introduction of the hemi-larynx setup has facilitated significant advances in the three-dimensional reconstruction of vocal fold dynamics Berry, 2006a, 2006b).…”