The Centre for Speech Technology Research, The university of Edinburgh

13 Mar 2001

Dr. Corine Astésano


Processing units in the production and perception of spoken French and English: Cross-linguistic and stylistic variability

Traditionally, French and English have been described as representing the two prototypes of respectively syllable-timed and stress-timed languages (Pike, 1945). In addition, the French accentual system is said to be characterized by a non-lexical final accent marked by lengthening, and congruent to prosodic boundaries. These characteristics have led some authors to consider French as a 'language without accent' (Rossi, 1980) or a 'boundary language' (Vaissière, 1991; Beckman, 1992). This (traditional) view stems from the fact that most phonological theories are based on laboratory speech (mostly isolated words), emphasizing the relationship between prosody and the syntactic properties of read speech. This dichotomy between syllable-timed and stress-timed languages is not supported by more recent investigations on spontaneous, natural speech. Indeed, many authors now reject this dichotomy and show that syllabic and accentual timing tend to coexist to various degrees in all languages. Other authors also point out the tendency for the 'traditional' final accentuation to coexist in French with a (melodic) word-initial accentuation, comparable to that of English (see Astésano, 1999 for references).

We subscribe to this latter conception of French prosody, because our research indicates that laboratory speech yields an incomplete view of the characteristics of French. Though difficult to study in a controlled way, continuous speech in natural situations of communication offers us a broader view of the realizations of linguistic categories, their natural functions, and the changes in the language. We thus propose to combine both a functionalist approach, encompassing various speaking styles (read, spontaneous and journalistic speech) and a generativist approach which posits a core linguistic system: in this view, the variability observed during the process of enunciation in various situations of communication reflects alloform expressions of this core system (Astésano, 1999). We adopt a phonological model of French prosody, which, while proposing a metrical frame of analysis, takes into consideration the descriptions of natural connected speech to account for the complexity of the French accentual system (Di Cristo, 1999). The model proposes that words are marked, in the underlying phonological structure, by an initial and a final accent, whose surface realization depends on grouping and rhythmic rules, as well as those pragmatic rules which account for nuclear and emphatic accent assignment.

Our analyses have revealed the existence of a relevant phonological unit for the prosodic characterisation of French: the Complex Prosodic Word (CPW), constituted of 2 Metrical Feet (MF), the first ending in a Word-Initial accent, the second ending in a final accent. This phonological unit is a cohesive rhythmic 'figure' and a reference unit for read speech as well as spontaneous speech, insofar as its duration is less variable than that of the syllable. This tendency is particularly marked for spontaneous speech, and expresses a tendency towards stress-timing, which appears to be even more salient in French than syllable-timing. We have thus shown that initial accentuation not only belongs to the accentual system of French but that it is also central to a description of the metrical properties of this language. Moreover, our results on infra-syllabic duration indicate that the CPW is phonetically clearly defined: the (lexical) initial accents are characterized by a significant lengthening of the Onset element over the Rime, whereas the reverse is true for the final accents. This tendency was also described for English (Campbell, 1992).

These results have important implications not only for the development of phonological theories but also for their psycholinguistic consequences, particularly as regards to the issue of speech segmentation and lexical access. Indeed, taking into consideration the initial accent in the metrical structure of French allows us to suggest that stress-timing should also play a role for lexical access in French. That is, instead of assuming that every syllable has equal potential as word-beginning for the listener (Dumay et al., 1999), we suggest that the syllables bearing a word-initial accent are most likely to play this role. In fact it may be that the CPW defined by an initial and a final accent, and not the Prosodic Word delimited by a sole final accent, is the basic metrical pattern in French, thus contradicting the traditional conception of speech segmentation in French (Cutler, 1999; Banel et al., 1998). The present project aims at testing this latter hypothesis. We designed a set of experiments to further test the relevance of the CPW as an encoding unit in French (Production priming experiment) and to pinpoint its function in the decoding processes (Gating and word-monitoring paradigms). Constant reference to equivalent research in English is made in this talk, although a systematic comparison between the two languages will come as a second step in the project. Indeed, a better understanding of the French phonological system needs first to be reached in order to allow a more insightful comparison between those two 'prosodically distant' languages.

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