Perceptual Distances of Breathy Voice Quality: A Comparison of Psychophysical Methods

Abstract

Objective Experiments to study voice quality have typically used rating scales or direct magnitude estimation to obtain listener judgments. Unfortunately, the data obtained using these tasks is context-dependent, which makes it difficult to compare perceptual judgments of voice quality across experiments. The present experiment describes a simple matching task to quantify voice quality. The data obtained through this task was compared to perceptual judgments obtained using rating scale and direct magnitude estimation tasks to evaluate whether the three tasks provide equivalent perceptual distances across stimuli. Methods Ten synthetic vowel continua that varied in terms of their aspiration noise were evaluated for breathiness using each of the three tasks. Linear and nonlinear regression was used to compare the perceptual distances between stimuli obtained through each technique. Results Results show that the perceptual distances estimated from matching and direct magnitude estimation task are similar, but both differ from the rating scale task, suggesting that the matching task provides perceptual distances with ratio-level measurement properties. Conclusions The matching task is advantageous for measurement of vocal quality because it provides reliable measurement with ratio-level scale properties. It allows the use of a fixed reference signal for all comparisons, thus allowing researchers to directly compare findings across different experiments.

A model for the prediction of breathiness in vowels

“…This is because the measurements across multiple experiments cannot be directly compared to one another. Alternate approaches to evaluate the perception of voice quality, such as the matching tasks (Gerratt and Kreiman, 2001;Patel et al, 2010) need to be developed and standardized. Second, more accurate algorithms need to be developed to decompose voices into its periodic and aperiodic components.…”

Psychometric properties associated with perceived vocal roughness using a matching task

“…Previous reports 6,8,9,11 have detailed several advantages of using a psychophysical matching task for measuring perceived voice quality across a range of stimuli and quality dimensions (i.e., breathiness, roughness). A factor critical to the success of the adaptive matching task is the range of roughness that can be supported by the comparison stimulus.…”

“…The two comparison stimuli used here are based on the comparison stimuli used by Patel et al 6,8 The carrier was a sawtooth wave with a fundamental frequency of 151 Hz that was low-pass filtered and mixed with noise. In one condition, the carrier was amplitude modulated with a sine function raised to the power of two, hereafter termed the "SQUARE" condition.…”

“…By avoiding these problems, a matching task is better suited for the perceptual study of voice quality. 6,7 Furthermore, perceptual judgments from a single-variable matching task provide ratiolevel data, as opposed to the ordinal data from rating scales, permitting more detailed mathematical treatment of the data.…”

“…In contrast, Patel et al have described a single-variable adaptive matching paradigm to quantify voice quality under laboratory conditions. This approach been tested for breathy 6,11 and rough 8 qualities. In this task, the magnitude of the voice quality of interest (e.g., roughness) is measured by comparing the test stimulus (the "standard") to a single reference stimulus (the "comparison").…”