Just-Noticeable Differences for Selected Aspects of Synthetic Fundamental-Frequency Contours
Dennis H. Klatt, Victor W. Zue · The Journal of the Acoustical Society of America · 1971
An A-B-X paradigm has been used to find the just-noticeable difference (jnd) for selected aspects of voice fundamental frequency (F0) contours by varying the F0 control parameter of a digitally simulated terminal analog speech synthesizer. Data have been obtained from three subjects for a number of 250-msec segments of the synthetic vowel /ɛ/ differing only in fundamental frequency. Results indicate that subjects are an order of magnitude less sensitive to changes in average F0 when the F0 contour shape is a linear descending ramp (jnd = 2.4 Hz) as opposed to a constant F0 contour (jnd = 0.3 Hz). Sensitivity to rate of change of F0 in linear ramps is surprisingly good; greatest sensitivity occurs when one ramp increases and the other decreases (jnd = 12 Hz/sec). High-pass filtering of the stimuli improves performance slightly, suggesting that the fundamental component is not involved in the detection of changes in F0. Substitution of the synthetic stimulus /ya/ with its nonconstant formant contours in place of /ɛ/ degrades performance only very slightly. [Work supported in part by an NIH grant.]