Perceptual equivalence of the Liljencrants-Fant and linear-filter glottal flow models

International audienceSpeech glottal flow has been predominantly described in the time-domain in past decades, the Liljencrants-Fant (LF) model being the most widely used in speech analysis and synthesis, despite its computational complexity. The causal/ anti-causal linear model (LF CALM) was later introduced as a digital filter implementation of LF, a mixed-phase spectral model including both anti-causal and causal filters to model the vocal-fold open and closed phases, respectively. To further simplify computation, a causal linear model (LF LM) describes the glottal flow with a fully causal set of filters. After expressing these three models under a single analytic formulation, we assessed here their perceptual consistency, when driven by a single parameter R d related to voice quality. All possible paired combinations of signals generated using six R d levels for each model were presented to subjects who were asked whether the two signals in each pair differed. Model pairs LF LM-LF CALM were judged similar when sharing the same R d value, and LF was considered the same as LF LM and LF CALM given a consistent shift in R d. Overall, the similarity between these models encourages the use of the simpler and more computationally efficient models LF CALM and LF LM in speech synthesis applications