Identifying a Comparison for Matching Rough Voice Quality

Purpose: Perceptual estimates of voice quality obtained using rating scales are subject to contextual biases that influence how individuals assign numbers to estimate the magnitude of vocal quality. Because rating scales are commonly used in clinical settings, assessments of voice quality are also subject to the limitations of these scales. Instead, a matching task can be used to obtain objective measures of voice quality, thereby facilitating model development and tools for clinical use. Method: Twenty-seven individuals participated in a rating task or at least 1 of 3 matching tests (named after their modulation functions: SINE, SQUARE, POWER) to quantify the degree of roughness in dysphonic voice stimuli. Participants evaluated the roughness of 34 voice samples using an amplitude-modulated complex carrier. Results: The matching thresholds were highly correlated with the ratings estimates. Reliability of thresholds did not significantly differ across tasks, but linear regressions showed that the POWER test resulted in larger perceptual distances. Conclusions: A matching task can be used to obtain reliable estimates of roughness in dysphonic voices. The POWER comparison is recommended because the variability in matching thresholds across the range of roughness was evenly distributed, and the perceptual distances between stimuli were maximized.