Are Instructions to Manipulate Specific Parameters of Laryngeal Function Associated with Auditory-Perceptual Ratings of Voice Quality in Nondisordered Speakers?

OBJECTIVES/HYPOTHESIS: This preliminary study investigated whether auditory-perceptual judgments of voice quality by experienced speech language pathologists were associated with instructions given to speakers to manipulate specific laryngeal postures.

STUDY DESIGN: Experimental, within-subject design.

METHODS: Nine speakers were instructed and trained to manipulate three vocal parameters implicated in functional voice disorders-false vocal fold constriction, vocal fold mass, and larynx height-while reading a standard passage. Experienced judges rated these standard passages in terms of the widely used perceptual voice qualities breathiness, roughness, vocal strain, glottal fry, tone onset, tone color, loudness, and pitch.

RESULTS: Between-subject factorial analysis of variance, controlling for judge unreliability, revealed some evidence that perceptual judgments are strongly associated with underlying laryngeal muscle activity that can then serve clinical planning of goals for intervention. Eta2 effect sizes were large for all dependent measures, ranging from 0.39 for pitch to 0.77 for strained.

CONCLUSIONS: Although these results are encouraging, they were obtained under ideal conditions. Further research is warranted.