Effects of Asymmetric Scarring in a Lumped-Mass Vocal System.

introductionVocal fold (VF) scarring following phonosurgical intervention alters tissue stiffness, damping, and inter-mass coupling, but whether these changes destabilize phonation through elevated stiffness or through inter-fold mechanical asymmetry has not been determined. Distinguishing these two mechanisms is clinically important because they implicate different therapeutic targets.

methodsA bilateral two-mass lumped VF model was used to simulate three conditions: a healthy symmetric baseline, a unilaterally scarred condition in which right-fold parameters (k, r, k

resultsThe healthy and bilateral scar conditions exhibited stable periodic oscillation with LLE below the 0.01 chaos threshold across all P

conclusionChaotic phonation concentrates mechanical loading on the scarred fold rather than distributing it to the contralateral fold, establishing a candidate mechanism for a self-perpetuating postsurgical injury cycle. The absence of chaos under bilateral symmetric scarring demonstrates that inter-fold mechanical asymmetry, rather than elevated stiffness alone, is the primary driver of chaotic phonation following VF scarring.