Analysis of a Soft Bio-Inspired Active Actuation Model for the Design of Artificial Vocal Folds

Abstract

Phonation results from the passively-induced oscillation of the vocal folds in the larynx, creating sound waves that are then articulated by the mouth and nose. Patients undergoing laryngectomy have their vocal folds removed and thus must rely on alternative sources of achieving desired vibration of artificial vocal folds. Existing solutions, such as voice prostheses and the Electrolarynx, are limited by producing sufficient voice quality, for instance. In this paper, we present the analysis of an active actuation model to replicate the vowels /a/, /e/, /i/, and /u/ and voice qualities of /vocal fry/, modal, /falsetto/, /breathy/, /pressed/, and /whispery/. These characteristics would be required as a first step to design an artificial vocal folds system. Dynamic equations are derived to identify the required forces to change the glottis area and frequencies to achieve sufficient oscillation of artificial vocal folds. Two types of Ionic polymer-metal composite (IPMC) actuators are used to assess their ability to produce these forces and the corresponding activation voltages required. The results of our proposed analysis will enable research into the effects of natural phonation and, further, provide the foundational work for the creation of advanced larynx prostheses.

Flow-induced oscillations of vocal-fold replicas with tuned extensibility and material properties

“…Today, the development of improved vocal-fold replicas and enriched experiments is still necessary to better understand the complexity of the multiphysical couplings involved, on the one hand, and to evaluate and dialogue with the various theories and numerical models mentioned above, on the other hand. Thus, in recent years, while improving current manufacturing procedures 45 , 46 , the search for optimal materials 47 – 49 , multi-scale structures 49 and mechanical control 50 , 51 for increasingly “bio-/phono-mimetic” vocal-fold replicas is the subject of active investigation. However: Even though vocal-fold stretching is a major aspect of phonation biomechanical control 3 , 32 – 35 , 39 , 52 , 53 , the number of in vitro studies involving experimental models of vocal folds able to measure and control the laryngeal longitudinal pre-strain occurring before any phonatory event is very limited.…”