Psychophysical evaluation of PSOLA: Natural versus synthetic speech

This paper presents the result of psychophysicalexperiments dealing with pitch-marker positioning withinthe Pitch Synchronous OverLap and Add (PSOLA)framework. Sustained natural vowels were PSOLAmodifiedin fundamental frequency. The experimentswere aimed at determining the auditory sensitivity to (1)deterministic shifts of either all or single pitch markerswithin a sequence, and (2) random shifts of all pitchmarkers niner"). As for deterministic shifts of all pitchmarkers, the results were in reasonable agreement withresults obtained previously for synthetic formant signals.For deterministic shifts of single pitch markers,thresholds depended on position in the sequence.Detection thresholds for jittered shifts were comparableto thresholds for detecting jitter in pulse trains. Theranking of the thresholds for these three conditionsindicated that the auditory system is more sensitive todynamic (modulation) cues rather than to static (timbral)cues arising from shifts in pitch-marker positioning.