Proposal of acoustic measures for automatic detection of vocal fry

Abstract

Vocal fry is a voice quality that often appears in relaxed voices indicating low tension, or in pressed voices expressing attitudes/feelings of surprise, admiration and suffering. We propose a set of acoustic measures for automatically detecting vocal fry segments in speech utterances. In order to deal with vocal fry utterances with very low fundamental frequencies, where classic short-term analysis methods become problematic, a glottal pulse synchronized method is proposed. The acoustic measures are based on power, periodicity and similarity properties of vocal fry signals. The basic idea is to scan for power peaks in a “very short-term” power contour, check for periodicity properties and evaluate a similarity measure between power peaks for deciding the possibility of vocal fry pulses. Sub-harmonic properties are also taken into account in the periodicity analysis. Evaluation of the proposed measures in automatic detection resulted in 73.3 % correct detection, with an insertion error rate of 3.9 %.