Objective Acoustic Quantification of Perceived Voice Tremor Severity

Area of Science:

• Speech and Hearing Sciences
• Acoustic Phonetics
• Clinical Audiology

Background:

• Vocal tremor is a common voice disorder characterized by rhythmic oscillations.
• Accurate assessment of vocal tremor severity is crucial for effective treatment.
• Current assessment relies on subjective auditory-perceptual judgments, necessitating objective measures.

Purpose of the Study:

• To compare auditory-perceptual ratings of vocal tremor with acoustic markers.
• To evaluate the concurrent and diagnostic validity of acoustic markers for vocal tremor.
• To develop and validate an acoustic model for quantifying vocal tremor severity.

Main Methods:

• Fifty-six sustained vowel recordings with vocal tremor were analyzed.
• Audiologists rated vocal tremor severity perceptually.
• Twelve acoustic measures of fundamental frequency (f0) and intensity level (IL) modulation were extracted using Praat.
• Multiple linear regression created an acoustic model of vocal tremor severity.

Main Results:

• Inter- and intra-rater reliability for perceptual ratings were acceptable (ICC=.72 and .83).
• Correlation between perceptual ratings and acoustic markers ranged from .11 to .76.
• The developed acoustic model showed a strong correlation (.89) with perceptual ratings.
• The acoustic model achieved high diagnostic validity (AUC=.93, sensitivity=.87, specificity=.91).

Conclusions:

• Auditory-perceptual ratings of vocal tremor are primarily influenced by f0 and IL modulation extent.
• The developed acoustic model demonstrates acceptable concurrent and diagnostic validity.
• External cross-validation is recommended before widespread clinical application of the acoustic model.