Objective: Strain and roughness are psychoacoustic percepts commonly used in auditory-perceptual voice evaluations. Numerous studies have investigated acoustic properties related to the perception of roughness, while fewer studies have investigated acoustic properties related to the perception of strain. Results from previous studies suggest there is an overlap in acoustic variables related to both the perception of strain and the perception of roughness. The present study seeks to investigate if it is possible to disentangle experienced listeners’ perception of strain and roughness through a paired-comparison task with multidimensional scaling analyses (MDS) and to identify acoustic correlates to emergent dimensions.

Methods/Design: Fifteen synthetic female singing voices were generated at each of the pitches A3 and F5 on the vowel /_/ with varying spectral source slopes of 0, -6, and -12 dB/octave to simulate varying levels of strain. A series of sine-wave amplitude modulations with modulation frequencies of 35 Hz and modulation depths of 0, -5, -10, -15, and -20 dB were superimposed on all synthetic voice stimuli to simulate varying levels of roughness, resulting in 15 stimuli at each pitch. The fifteen stimuli were paired in all possible combinations within each pitch for a total of 105 stimuli pairs at each pitch. Experienced listeners will be asked to rate the dissimilarity of each stimulus pair using a visual analog scale. MDS analyses will be conducted to visualize the perceptual dimensions hypothesized to be associated with the perception of strain and roughness. Linear regression analyses will be performed on the MDS solutions using acoustic variables to identify predictors of each dimension.

Results: Based on previous research indicating a relationship between spectral source slope and the perception of strain and a relationship between amplitude modulation depth and the perception of roughness, it is anticipated that, in the absence of a predetermined classification scheme, MDS solutions will represent experienced listeners’ perceptual spaces of strain and roughness, and that acoustic measures will emerge as predictors of specific dimensions.

Conclusion: Results from this study may improve our understanding of the psychoacoustics and potential interactions between the percepts of strain and roughness in experienced listeners.