Construction of perception stimuli with copy synthesis

International audienceA number of experiments in perception requires the construction of speech-like stimuli whose acoustic content needs to be manipulated easily. Formant synthesis offers the possibility of editing all the parameters of speech. However, the construction of stimuli by hand is a very laborious task and therefore automatic tools are necessary. This paper describes two main extensions of a copy synthesis algorithm previously proposed. The first concerns formant tracking which relies on a concurrent curve strategy. The second is a pitch synchronous amplitude adjustment algorithm that enables the capture of fast varying amplitude transitions in consonants. In addition, the automatic determination of the source parameters through the computation of F0 and of the friction to voicing ratio enables the speech signals to be copied automatically. This copy synthesis is evaluated on sentences and V-Stop-V stimuli

Burst segmentation and evaluation of acoustic cues

Colloque avec actes et comité de lecture. internationale.International audienceThis paper investigates burst segmentation for the evaluation of acoustic cues used to identify unvoiced French stops. Unlike other works which utilize a fixed length window, our approach consists in segmenting bursts into transient and frication noise. The transient is found by minimizing the sum of spectral variances of transient and frication noise over the burst. The spectral variance criterion has the advantage of being sensitive both to energy deviations and spectral variations. Additional correction procedures augment the robustness of the segmentation against the presence of spurious noises during the closure and the determination of the voicing onset with delay. The relevance of our segmentation method has been evaluated by comparing the characteristics of the main spectral peak (energy prominence versus frequency) in the transient segmented by our method with those of the full burst. Our experiments showed that bursts segmented by our method allow a better discrimination between the three places of articulation