Jitter, Shimmer, and Noise in Pathological Voice Quality Perception

Although jitter, shimmer, and turbulent noise characterize all voice signals, their perceptual importance has not been established psychoacoustically. To determine which of these acoustic attributes is important in listeners’ perceptions of pathologic voices, listeners used a speech synthesizer to adjust levels of jitter, shimmer, and noise so that synthetic voices matched natural pathological voices. Results show that listeners perceived spectrally-shaped, additive noise as the critical inharmonic acoustic element contributing to pathologic voice quality. Listeners proved highly insensitive to the amounts of jitter and shimmer present in a voice sample. These results suggest that jitter and shimmer are not useful indices of voice quality.