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oai:recercat.cat:20.500.14342/51562025-03-21T04:26:11Zcom_2072_482405com_2072_183628col_2072_482415

00925njm 22002777a 4500 dc Guasch, Oriol author Van Hirtum, Annemie author Fernandez, Ana Ines author Arnela, Marc author 2022-06 Human phonation is a highly non-linear process in which subglottal flow emanating from the lungs induces self-oscillations of the vocal folds. In normal conditions, this results in the generation of a regularly pulsating volume velocity that becomes the source of acoustic waves, which once modulated by the vocal tract, get emitted outwards as voice. However, vocal fold oscillations can become chaotic under many circumstances. For instance, even in the case of healthy symmetric vocal folds, an excess value of the subglottal pressure can trigger chaotic motion. In this paper, we derive a chaos control strategy for a two-mass model of the vocal cords to revert the situation and render the motion regular again. The approach relies on slightly altering the system energy to move it to a stable state. Given that no external control forces can be applied to the vocal cords, it is proposed to add a third mass to the original two-mass model, which is assumed to be made of an ideal smart material. The mass of the smart material is presumed negligible in comparison to the two masses of the vocal folds model, but its damping and stiffness can be tuned to evolve with time. For a fixed subglottal pressure for which the motion is chaotic, it is shown how periodicity can be recovered using adequate damping laws, by either attaching the smart material onto the larger vocal fold mass or onto the smaller one. For the latter, chaos control turns to be more difficult and the damping of the smart material has to quickly vary with time. On the other hand, given that the subglottal pressure would rarely be constant in a real situation, we also introduce a damping law to avoid chaotic motion as the subglottal pressure augments or diminishes. Finally, it is shown that control can not only be achieved by acting on the damping of the smart material but also on its stiffness. A stiffness law to prevent chaotic oscillations and get a healthy pulsating volume velocity is therefore implemented. A brief discussion on the mid-long term potential of the presented solution for practical cases is included. 0960-0779 http://hdl.handle.net/20.500.14342/5156 https://doi.org/10.1016/j.chaos.2022.112188 Vocal fold pacemaker Vocal fold dynamics Chaotic self-oscillations Chaos control Smart materials Two-mass models Marcapassos de cordes vocals Dinàmiques de cordes vocals Autooscil·lacions caòtiques Control del caos Materials intel·ligents Models de dues masses Controlling chaotic oscillations in a symmetric two-mass model of the vocal folds