Effects of the Epilarynx Area on Vocal Fold Dynamics and the Primary Voice Signal

Abstract

For the analysis of vocal fold dynamics, sub- and supra glottal influences must be taken into account, as recent studies have shown. In this work, we analyze the influence of changes in the epi-laryngeal area on vocal fold dynamics. We investigate two excised female larynges in a hemi-larynx set-up combined with a synthetic vocal tract consisting of hard plastic and simulating the vowel /a/. Eigenmodes, amplitudes, and velocities of the oscillations, the sub-glottal pressures and sound pressure levels of the generated signal are investigated as function of three distinctive epi-laryngeal areas (28.4 mm2, 71.0 mm2 and 205.9 mm2). The results showed that the sound-pressure level is independent of the epi-larynx cross-section and exhibits a non-linear relation to the insufflated air flow. The sub-glottal pressure decreased with an increase in the epi-laryngeal area and displayed linear relations to the air flow. The principal eigenfunctions from the vocal fold dynamics exhibited lateral movement for the first Eigenfunction and rotational motion for the second Eigenfunction. In total, the first two Eigenfunctions (EEF) covered a minimum of 60% of the energy, with an average of more than 50% for the first Eigenfunction. Correlations to epilarynx areas were not found. Maximal values for amplitudes (up to 2.5 mm) and velocities (up to 1.57 mm/ms) changed with varying epilaryngeal area, but did not show consistent behaviour for both larynges. We conclude that the size of the epi-laryngeal area has significant influence on vocal fold dynamics, but does not significantly affect the resultant sound-pressure level.

Interaction between epilaryngeal and laryngeal adjustments in regulating vocal fold contact pressure

“…For example, epilaryngeal narrowing in this study leads to a significant energy boost (as large as 15–20 dB) in the 2–3 kHz range in the voice spectra, similar to that in previous studies ( Sundberg, 1974 ; Titze and Story, 1997 ). The reduction in the glottal flow rate with epilaryngeal narrowing is consistent with the observations in Titze (2002) , Döllinger et al (2006 , 2012) , and Samlan and Kreiman (2014) . Samlan and Kreiman (2014) also showed the MFDR decreased with epilaryngeal narrowing, which is similar to the observations in our study for conditions of strong epilaryngeal narrowing.…”

“…Our results also show that epilaryngeal narrowing generally has a small effect on the mean and peak-to-peak amplitude of the glottal area waveform. This suggests that the observed changes in the peak contact pressure are in a large part due to subtle changes in vocal fold vibration dynamics induced by epilaryngeal narrowing (e.g., Döllinger et al , 2012 ).…”

Dynamic vocal fold parameters with changing adduction in ex-vivo hemilarynx experiments

“…18 Furthermore, higher airflow, f 0 , and SPL were found with increasing P S values. 39 Based on a preliminary, single ex-vivo hemilarynx study, D€ ollinger & Berry 24 hypothesized that subglottal pressure and flow rate were not significantly influenced by increasing (posterior) vocal fold adduction (levels at 10, 20, and 50 g). However, the present study of three human excised larynges with a larger range of applied adduction forces (10, 50, 100 g) showed a large impact.…”

“…Its aim is to study vocal fold dynamics 5,18,19,37 and the influence of the supraglottal tract on vocal fold dynamics. 38,39 For convenience, the applied ex-vivo setup described in detail previously 17,23,24 is briefly outlined below.…”

In Vivo Measurement of Pediatric Vocal Fold Motion Using Structured Light Laser Projection

“…An alternate approach that simplifies the calibration is to use the distance between two laser dots as the reference. 10,11,24,26,27 Because the two laser dots projected at a fixed distance apart do not diverge significantly, the distance between the dots in the image can be used as a ruler. The two-dot systems have the same difficulty of the laser spot detection and targeting as the one-dot instruments.…”