An algorithm to measure vocal tremor is presented, validated, and applied. The expected input is a sound file that captures a sustained phonation. The 6 output values are the frequency of frequency and amplitude tremor, intensity indices of frequency and amplitude tremor, and power indices of frequency and amplitude tremor. Basic principles of the algorithm are (1) autocorrelations of pitch and amplitude contours that are based on an autocorrelation of the input signal, (2) the correction for declination of (natural) contours as well as (3) a contour peakpicking and -averaging method for the determination of tremor intensities. The tremor power indices are new measures that weight tremor intensities by tremor frequency in order to receive bio- and psychologically more significant measures of tremor magnitude. The algorithm is implemented as a script of an open-source speech analysis program providing an most accurate pitch-detection (autocorrelation) method.
Index Terms: acoustic voice analysis, vocal tremor, vibrato, modulation
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Bibliographic reference. Brückl, Markus (2012): "Vocal tremor measurement based on autocorrelation of contours", In INTERSPEECH-2012, 715-718.