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Jitter and Shimmer

Jitter and shimmer are acoustic measures of frequency and amplitude perturbation, respectively, and derive from involuntary short-term vocal instability. Jitter describes cycle-to-cycle variability in fundamental frequency (F0) that cannot be explained on the basis of voluntary changes in F0, while shimmer is a measure of involuntary changes in peak amplitude across adjacent phonatory cycles.

Both measures are used in voice clinics as part of comprehensive assessments of laryngeal and vocal function, alongside visual examinations of the larynx, and perceptual voice assessments. This practice is based on a sizable body of literature that has shown that frequency and amplitude perturbation are associated with the perception of hoarse, harsh, or rough voice qualities and can function as valid predictors of vocal pathology when combined with other measures. ...

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