Acoustic and perceptual characteristics of voice tremor: A systematic review.

This systematic review synthesised evidence on the acoustic and perceptual characteristics of voice tremor (VT) in the adult population, the speech tasks used in VT evaluations, and the impact of VT on quality of life (QoL). Following PRISMA guidelines, 58 studies were included and assessed for risk of bias. Acoustically, VT is consistently characterised by rhythmic modulation of frequency and amplitude. Secondary acoustic measures, including jitter, shimmer, noise, and cepstral measures, demonstrate fluctuations in VT, but are not defining features. Perceptually, listeners show greater sensitivity to the extent of modulation than to the rate of frequency and amplitude. There were no definitive aetiology-specific patterns. Sustained vowel phonation best captures VT, whereas connected speech tends to mask modulation despite providing ecological validity. A significant gap was identified in QoL evaluations, limiting the holistic understanding of VT. Overall, the included studies show a moderate to low risk of bias.