Measurement of speech disfluency through magnitude estimation and interval scaling

The purpose was to assess whether equal-appearing interval or magnitude-estimation scaling resulted in a data set with a closer correlation to the physical stimuli, made up of speech samples with varying amounts of disfluency. 20 young adults completed two tasks. In Task 1, subjects used a 7-point equal-appearing interval scale to rate the disfluency of 10 speech samples having varying within sentence pause, presented randomly at 65 dB SPL. In Task 2, subjects used magnitude-estimation scaling to rate these stimuli, presented in a randomized order. Analysis showed significantly high correlations for both scaling techniques and the speech stimuli (Spearman rho=.90 and 1.00, respectively). It appears that subjects can use either scaling technique to rate accurately varied speech disfluency.