Objectives/hypothesis: The quality of tracheoesophageal voice can vary substantially. Although previous research has identified acoustic differences between various types of voicing (i.e., laryngeal, tracheoesophageal, esophageal, etc.), acoustic analysis has failed to quantify the degree of alaryngeal voice quality. This study assessed the value of several cepstral, spectral, and perturbation measures in quantifying the overall quality of tracheoesophageal voice production.
Study design: Cross-sectional, correlational.
Methods: Continuous speech and sustained vowel samples from 16 tracheoesophageal speakers were concatenated and perceptually rated in a paired comparison paradigm on overall voice quality by four experienced clinicians. After removing the nonvoiced fragments within the continuous speech samples, the concatenated samples were analyzed with 47 perturbation, spectral, and cepstral measures. Correlation between perceptual ratings and acoustic measures was assessed. Multiple regression analysis resulted in a two-factor acoustic model for the measurement of overall voice quality of the concatenated samples.
Results: The reliability of the perceptual judgements was moderate to high. The prominence of the cepstral peak (CPP) and of the first two spectral harmonics appeared to be the strongest correlates of tracheoesophageal voice quality. A linear regression-based combination of CPP and the height of the second harmonic produced a correlation of 0.87 with listener judgments.
Conclusions: It is clinically feasible to investigate both continuous speech and sustained vowel samples of tracheoesophageal speakers with acoustic methods described and assessed in this report. Results are discussed in the context of existing literature.