The Acoustic Voice Quality Index: toward improved treatment outcomes assessment in voice disorders

Voice practitioners require an objective index of dysphonia severity as a means to reliably track treatment outcomes. To ensure ecological validity however, such a measure should survey both sustained vowels and continuous speech. In an earlier study, a multivariate acoustic model referred to as the Acoustic Voice Quality Index (AVQI), consisting of a weighted combination of 6 time-, frequency- and quefrency-domain metrics, was developed to measure dysphonia severity in both speaking tasks. In the current investigation, the generalizability and clinical utility of the AVQI are evaluated by first assessing its external cross-validity and then determining its sensitivity to change in dysphonia severity following surgical and/or behavioral voice treatment. The results, based upon a new set of normal and disordered voices compared favorably with outcomes reported earlier, indicating acceptable external validity. Furthermore, the AVQI was sensitive to treatment-related changes, validating its role as a potentially robust and objective voice treatment outcomes measure.

Readers will be able to: (1) explain methodological issues surrounding the development of voice treatment outcomes measures (such as external cross-validity and responsiveness to change), (2) appreciate the relevance of measuring dysphonia severity in both sustained vowels and connected speech, (3) describe the method of obtaining the Acoustic Voice Quality Index (AVQI), (4) appreciate differences among a variety of estimates of diagnostic accuracy, and (5) discuss the AVQI as a clinically valid treatment outcomes measure.