Using Pitch Height and Pitch Strength to Characterize Type 1, 2, and 3 Voice Signals

Classifying dysphonic voices as type 1, 2, and 3 signals based on their periodicity enables researchers to determine the validity of acoustic measures derived from them. Existing methods of signal typing are commonly performed by listening to the voice sample and visualizing them on narrow-band spectrograms that require training, time, and are subjective in nature. The current study investigated pitch-based metrics (pitch height and pitch strength) as correlates to characterizing voice signal types. The computational estimates were validated with perceptual judgments of pitch height and pitch strength.

Pitch height and pitch strength were estimated from Auditory-Sawtooth Waveform Inspired Pitch Estimator Prime algorithm for 30 dysphonic voice segments (10 per type). Ten listeners evaluated pitch height through a single-variable matching task and pitch strength through an anchored magnitude estimation task. One way analyses of variance were used to determine the effects of signal type on pitch height and pitch strength estimates. Relationship between computational and perceptual estimates was evaluated using correlation coefficients and their significance.

There was a significant difference between signal types in both computational and perceptual pitch strength estimates. Periodic type 1 signals had greater pitch strength compared to type 2 and 3 signals. Auditory-Sawtooth Waveform Inspired Pitch Estimator Prime produced robust computational estimates of pitch height even in type 3 signals when compared to other acoustic software. Listeners were able to reliably judge pitch height in type 2 and 3 signals despite their lack of a clear fundamental frequency.

Pitch height and pitch strength can be measured in all dysphonic voices irrespective of signal periodicity.