Pitch-synchronous decomposition of mixed-source speech signals

Abstract

As part of a study of turbulence-noise sources in speech production, a method has been developed for decomposing an acoustic signal into harmonic (voiced) and anharmonic (unvoiced) components, based on a hoarseness metric [Muta et al., J. Acoust. Soc. Am. 84, 1292–1301 (1988)]. Their pitch-synchronous harmonic filter (PSHF) has been extended (to EPSHF) to yield time histories of both harmonic and anharmonic components. These corpus include many examples of turbulence noise, including aspiration, voiced and unvoiced fricatives, and a variety of voice qualities (e.g., breathy, whispered). The EPSHF algorithm plausibly decomposed breathy vowels, but the harmonic component of voiced fricatives still contained significant noise, similar in shape to (though weaker than) the ensemble-averaged anharmonic spectrum. In general, the algorithm performed best on sustained sounds. Tracking errors at rapid transitions due to jitter and shimmer were spuriously attributed to the anharmonic component. However, the extracted anharmonic component clearly exhibited modulation in voiced fricatives. While such modulation has been previously reported (and also in hoarse voice), it was verified by tests on synthetic signals, where constant and modulated noise signals were extracted successfully. The results suggest that the EPSHF will continue to enable exploration of the interaction of phonation and turbulence noise.