A mi-chemin entre analyse complexe et superanalyse

In the framework of superanalysis we get a functions theory close to complex analysis, under a suitable condition (A) on the real superalgebras in consideration (this condition is a generalization of the classical relation 1 + i^2 = 0 in C). Under the condition (A), we get an integral representation formula for the superdifferentiable functions.We give a result of Hartogs type of separated superdifferentiability, a continuation theorem of Hartogs-Bochner type and a Liouville theorem for the superdifferentiable functions.Comment: version 2 : \`a para\^itre dans Publicacions Matem\`atiques (compl\'ements par rapport \`a la version 1 : commentaires sur les conditions alg\'ebriques

Entre analyse complexe et superanalyse

In the framework of superanalysis we get a functions theory close to complex analysis, under a suitable condition (A) on the real superalgebras in consideration. Under the condition (A), we get an integral representation formula for the superdifferentiable functions.We give a result of Hartogs type of separated superdifferentiability and a continuation theorem of Hartogs-Bochner type for the superdifferentiable functions.Comment: v2 correspond \`a l'article d\'etaill\'e pour une note aux CRAS (v3) parue en 200

Automatic Feedback for L2 Prosody Learning

International audienceWe have designed automatic feedback for the realisation of the prosody of a foreign language. Besides classical F0 displays, two kinds of feedback are provided to learners, each of them based upon a comparison between a reference and the learner's production. The first feedback, a diagnosis, provided both in the form of a short text and visual displays such as arrows, comes from an acoustic evaluation of the learner's realisation; it deals with two prosodic cues: the melodic curve, and phoneme duration. The second feedback is perceptual and consists in a replacement of the learner's prosodic cues (duration and F0) by those of the reference. A pilot experiment has been undertaken to test the immediate impact of the "advanced" feedback proposed here. We have chosen to test the production of English lexical accent in isolated words by French speakers. It shows that feedback based upon diagnosis and speech modification enables French learners with a low production level to improve their realisations of English lexical accents more than (simple) auditory feedback. On the contrary, for advanced learners involved in this study, auditory feedback appears to be as efficient as more elaborated feedback

Assimilations de voisement et interférences français/allemand

Session : Phonétique, PhonologieInternational audienc

Voicing assimilations by French Speakers of German in stop-fricative sequences

International audienceVoicing assimilations inside groups of obstruents occur in opposite directions in French and German, where they are respectively regressive and progressive. The aim of the study is to investigate (1) whether non native speakers (here French learners of German) are apt to acquire subtle L2 specificities like assimilation direction, although they are not aware of their very existence, or (2) whether their productions depend essentially upon other factors, in particular consonant place of articulation. To that purpose, a corpus made up of groups of obstruents (/t/ followed by /z/, /v/ or /f/) embedded into sentences has been recorded by 16 French learners of German (beginners and advanced speakers). The consonants are separated by a word or a syllable boundary. Results, derived from the analysis of consonant periodicity and duration, do not stand for an acquisition of progressive assimilation, even by advanced speakers, and do not show differences between the productions of advanced speakers and beginners. On the contrary the boundary type and the consonant place of articulation play an important role in the presence or absence of voicing inside obstruent groups. The role of phonetic, universal mechanisms against linguistic specific rules is discussed to interpret the data

Acoustic correlates of L2 prosodic boundaries by German learners of French

International audienceDeviations in L2 intonation affect a number of prosodic characteristics including pitch range, declination line, or the rises of non-final IPs, and might lead to misunderstandings or contribute to the perception of foreign-accent. This study investigates the characteristics of non-native speech at the boundary between prosodic constituents. We analyzed a French declarative sentence, extracted from the IFCASL corpus (www.ifcasl.org), made up of four constituents and pronounced with a neutral intonation. Each constituent has three syllables and the sentence is realized typically by French speakers with four accentual –prosodic- groups, corresponding to the four constituents. Fourty German learners of French (beginners, and advanced speakers) and fifty four French speakers read the sentence once. We used the software ProsodyPro from Yi Xu for the prosodic analysis. We determined the presence of pauses and evaluated for each prosodic group: the (normalized) F0 maximum on the last syllable; the F0 excursion (max-min) of the final contour, and its maximum of velocity. In order to analyze the temporal course of F0 on the final contour, we also compared the values of the F0 excursion on the vowel and before it. On the basis of acoustic cues, non-native speakers, especially beginners, appear to realize more important prosodic boundaries (in particular higher F0 maxima, especially at the very end of the prosodic group, and more pauses) than French speakers, whereas native speakers appear to show more anticipation

A phonetically-guided diagnosis of auditory deficiency based on synthetic speech stimuli

Colloque avec actes et comité de lecture.We propose a phonetically-guided diagnosis of auditory deficiency, which hinges on a carefully constructed corpus of synthetic sounds. Our aim is to complement the diagnosis of sensorineural hearing deficiencies, in order to improve the correction afforded by auditory prosthesis. We first design a vowel corpus, based upon pairs of two-formant, steady-state synthetic French vowels, where the vowels of each pair are chosen to differ only in the frequency of one of their two formants. To test our method, we simulate a frequency-selective loss of audibility, by specifying a piece-wise linear audibility curve with a minimum of -40 dB at a given centre-frequency (1.3, 1.6, and 1.9 kHz). Results of perceptual experiments with normal hearing people tend to show that our synthetic data set is amenable to the diagnosis of the frequency region where the simulated hearing problem is most acute

A copy synthesis method to pilot the Klatt synthesiser

Colloque avec actes et comité de lecture. internationale.International audienceThis paper presents a copy synthesis method to controlling the Klatt synthesizer. Our method allows speech stimuli to be constructed very easily. We accepted the parallel branch of the Klatt synthesizer. After formants have been tracked, the amp litudes of the resonators are measured on a spectrum obtained by an algorithm derived from cepstral smoothing called ''true e nvelope''. This algorithm has the advantage of approximating harmonics very accurately. The analysis strategy of a speech sig nal is straightforward: the fundamental frequency is calculated so that voiced regions are known and the frication energy is set to the value of the spectral energy above 4000 Hz. Stimuli which have been created by means of this method have a timbre close to that of natural speech. This copy synthesis method is incorporated in our software for speech research called ``Sno rri''. Therefore, the user has at his disposal a versatile tool for creating stimuli in the context of the Klatt synthesize

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

Segmentation du bruit d'explosion des occlusives

Colloque avec actes et comité de lecture. nationale.National audienceThis paper investigates burst segmentation for the evaluation of acoustic cues used to identify unvoiced French stops. Unlike 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 variation criterion has the advantage of being sensitive both to energy deviations and spectral variations. Additional correction procedure 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 all burst. Our experiments showed that bursts segmented by our method allow a better discrimination between the three places of articulation