Cycle to cycle spectral perturbations in the voices of male and female speakers

The glottal function was obtained through the use of a reflectionless tube. This tube acted as a pseudoinfinite termination of the vocal tract. Male and female speakers phonated a neutral vowel while target matching to a 125- and a 210-Hz tone, respectively. The glottal waveform was digitized at 40k samples/s and each cycle was partitioned at zero crossings. This procedure provided an accurate determination of the period of each glottal pulse. Discrete Fourier analysis on each individual cycle indicated changes in the spectral content. The amplitude and phase of the first ten harmonics were utilized to obtain separate perturbation values as well as an overall amplitude measure. The data showed a systematic change in the spectral character of the sustained vowel source signal. Spectral perturbation analaysis may be a more inclusive measure of waveshape changes than jitter or shimmer.