1. The distribution of the duration of the 4185 schwas (fig.2) is divided into 2 sub- groups : (1) 29% of the words produced with a complete absence of voicing & formant structure, i.e. forms realized without a vocalic portion (e.g. fig. 3) (2) 71% of the occurrences present a vocalic portion corresponding to a schwa, i.e. forms realized with a vocalic portion (e.g. fig. 4). (The distribution of the duration of these schwa-full forms is unimodal and close to normality.) The distribution of schwa duration is not continuous but present a gap in the distribution between 0 and 16 ms. ON THE CATEGORICAL NATURE OF THE PROCESS INVOLVED IN SCHWA ELISION IN FRENCH A. Bürki¹², C. Fougeron¹ & C. Gendrot¹ ¹Laboratoire de Phonétique et Phonologie, UMR 7018, CNRS-Paris 3/Sorbonne Nouvelle, France ²Laboratoire de Psycholinguistique Expérimentale, Université de Genève, Suisse Schwa elision in French = alternation between 2 variants of a same lexical entry with or without its schwa, e.g. ‘fenêtre’ (window) pronounced either with a schwa-full form [f  t  ] or with a schwa-less form [f  t  ]. Traditional phonological accounts assume that this alternation process is complete and results from a rule- based segmental process. Aim: Aim: determining whether experimental evidence can be found to assess the categorical nature of this process by analyzing the different realizations of words containing a schwa in the ESTER corpus (Galliano & al., 2005). (1)Creation of a repertory of 18553 French words containing a schwa. (2)Selection of words recognized by the IRISA automatic recognition system as being produced in the corpus in their schwa-less and schwa-full forms. (3)Manual examination and correction of the output of the automatic recognition system. I. INTRODUCTION IV. DISCUSSION AND CONCLUSION Figure 1: Schwa-full occurrence of the word ‘semaine’ (week). Manual segmentation according to the determined criteria. Interpretation Interpretation : The distribution of schwa duration is explained by both a categorical and a gradual process.  a phonological categorical alternation process accounts for the leftmost mode of the distribution and the gap between the 2 groups.  a gradual phonetic process of reduction accounts for the gradual temporal reduction within the rightmost group of the schwa-full forms. A thorough analysis of the 1215 occurrences included in the leftmost mode (categorized as schwa-less) is needed to confirm our interpretation.  The bimodal distribution seems to support the categorical nature of the process.  However, the gap between the two groups could be a by-product of the criteria chosen to define the acoustical interval corresponding to schwa. Nonetheless, modifying our segmentation criteria to include realizations such as fig. 5 would not have changed the distribution to support a continuous gradual process. ( If realizations such as fig. 5 were categorized as schwa-full, it would not inflate the distribution in the gap region, but rather the left tail of group 2.) Figure 5: Realization of the word ‘avenir’ (future). The portion of increased intensity between [v] and [n] (25ms) could be attributed to a devoiced vowel. Figure 3 and 4: Schwa-less (left) and schwa-full (right) occurrences of the word ‘sera’ (will be). Schwa duration Nb of occurrences Figure 2: Distribution of the schwa durations gap (1) (2) Criteria for determining the presence/duration of schwa : -Realized schwa: voiced portion + formant structure -Onset and offset of the vowels: determined on signal periodicity and apparition / disappearance of F2 (Figure 1). (4) Analysis of the schwa durations of these words Research question: Research question: Does the realizations of schwa follow a continuous pattern of reduction ranging from a full vowel realization to a fully absent vowel, or do two categories emerge : full vowels on one side, and completely deleted vowels on the other side?  Prediction for a categorical alternation process: bimodal distribution of the schwa durations, with a gap between 2 groups (schwa-full and schwa-less forms).  Prediction for a gradual reduction process: continuous distribution towards 0 duration (i.e. schwa-less form = end-point of the gradual reduction process). III. RESULTS II. METHOD The distribution of the duration of the 4185 schwas (fig.2) is divided into 2 sub- groups : (1) 29% of the words produced with a complete absence of voicing & formant structure, i.e. forms realized without a vocalic portion (e.g. fig. 3) (2) 71% of the occurrences present a vocalic portion corresponding to a schwa, i.e. forms realized with a vocalic portion (e.g. fig. 4). (The distribution of the duration of these schwa-full forms is unimodal and close to normality.) The distribution of schwa duration is not continuous but present a gap in the distribution between 0 and 16 ms. IV. DISCUSSION AND CONCLUSION