Sensitivity of Elastic Properties to Measurement Uncertainties in Laryngeal Muscles With Implications for Voice Fundamental Frequency Prediction

Abstract

Objectives/Hypothesis-This paper discusses the effects of measurement uncertainties when calculating elastic moduli of laryngeal tissue.Methods-Small dimensions coupled with highly nonlinear elastic properties exacerbate the uncertainties. The sensitivity of both tangent and secant Young's Modulus was quantified in terms of the coefficient of variation, which depended on measurement of reference length and crosssectional area.Results-Uncertainties in the measurement of mass, used to calculate cross-sectional area of a small tissue sample, affected Young's Modulus calculations when tissue absorption of the hydrating solution was not accounted for. Uncertainty in reference length had twice the effect on elasticity than other measures.Conclusions-The implication of these measurement errors on predicted fundamental frequency of vocalization is discussed. Refinements on isolated muscle experimental protocols are proposed that pay greatest attention to measures of highest sensitivity.

Cervids with different vocal behavior demonstrate different viscoelastic properties of their vocal folds

“…In an earlier study, measurement errors of tissue mass and tissue length have been identified as having the most deteriorating effect for stress calculations (Hunter et al, 2007). We attempted to minimize such effects by using a relatively large sample size.…”

“…We, therefore, corrected all mass measurements by 12% (in both experiments) because our mass measurements were taken after the experiment. We adapted density values from an earlier study on human vocal folds (Min et al, 1995) because Hunter et al (2007) demonstrated that small variations in density have a negligible effect on stress calculations.…”

Vocal fold elasticity of the Rocky Mountain elk (Cervus elaphus nelsoni) – producing high fundamental frequency vocalization with a very long vocal fold

“…Three measurement uncertainties in laryngeal tissue (tissue weight, length and density) have been identified as important for the sensitivity of elastic properties (Hunter et al, 2007). Mass measurements are uncertain due to hydration (tissue bath, see above) of the isolated tissue.…”

Histological Organization is Similar in Human Vocal Muscle and Tongue—A Study of Muscles and Nerves

“…Moreover, the TA muscle is the only muscle that selectively controls different parts of the vocal fold. Thus, the selective control of different regions of the vocal fold can be explained, at least in part, by fact that the organization of muscle fibers in the TA 10,23,24 is similar to that seen in the TO muscles. Furthermore, their results can be considered as general reference points for future studies aimed at further elucidating the relationship between peripheral nerve regeneration and any possible relation to the pathogenesis of diseases, such as idiopathic laryngeal hemiparalysis and hemiatrophy of the TO muscles.…”

“…Thus, when the insertion and origin surfaces of a muscle are not parallel to each other, the fibers on one side of the sample are different in length from those on the other side. 24 Innervation is another very important aspect of the TA and TO muscles. Classical studies report that in addition to innervating the TA muscle, the X also innervates the palatoglossus, an important muscle of the tongue.…”