Influence of level difference due to vocal folds angular asymmetry on auto-oscillating replicas

Abstract

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Imaging of auto-oscillating vocal folds replicas with left–right level difference due to angular asymmetry

“…Recently, a physical study using mechanical VF replicas (Fig. 1) was presented in order to experimentally study the effect of air leakage solely due to vertical left-right angular asymmetry on features commonly associated with voice quality [10]. Concretely, the right VF was kept in place (the normal one) whereas the left VF (the paralyzed one) is tilted with asymmetry angle α in its sagittal plane as illustrated in Fig.…”

“…Experiments were performed using three different (M5, MRI and EPI) deformable multi-layer silicone VF replicas [11,12,13,14,15] depicted in Fig. 1 [10,16]. Increasing the asymmetry angle α (up to 25 • ) increases the glottal leakage area (red triangle in Fig.…”

“…The shape and tension of each VF are unaltered by the imposed asymmetry angle α. It followed that the degree of contact between the medial surfaces of the left and right VF decreases and eventually ceases with α [10,16].…”

“…For all three replicas, it was found [10,16] that when α and hence glottal leakage increases, the oscillation frequency f 0 reduces monotonically with at least 10% while both VFs remain in partial contact and even more so when contact between both VFs ceases. This finding offers an interesting new perspective on frequency changes related to UVFP.…”

“…This finding offers an interesting new perspective on frequency changes related to UVFP. Indeed, whereas clinical studies generally attribute its symptomatic low frequency voice solely to decreased tension in the paralysed vocal fold [1,17], this physical study [10] (a) simplified left human VF (b) deformable silicone VF replicas Figure 1: Multi-layered VF structure: a) left human VF in the medio-frontal plane based on [1], b) deformable silicone VF replicas M5, MRI and EPI [10] for α = 0 • . shows that frequency reduction might be partly correlated to increased air leakage due to angular asymmetry.…”