Processing liaison consonants in French: new acoustic and perceptual data

Processing liaison consonants in French: new acoustic and perceptual data Noël Nguyen1, Sophie Wauquier-Gravelines2, Leonardo Lancia3, & Betty Tuller4 Lab. Parole et Langage, CNRS & Univ. Provence, France Lab. for Linguistics, Univ. Nantes, France Center for Complex Systems and Brain Sciences,Florida Atlantic University, USA

Introduction This work is concerned with the well-known phenomenon of liaison in French. We aim to better understand how liaison is processed by listeners. One of our objectives was to determine whether or not liaison consonants are perceived as having the same phonological status as non-liaison consonants. Two experiments were designed to assess different predictions made on the basis of two competing phonological theories of liaison.

Liaison in French Liaison: appearance of a consonant (liaison consonant, LC) at the juncture of two words, which otherwise are not pronounced with that consonant  Word1 – LC – Word 2 examples: • petit ours [] « small bear » • les amis [] « the friends » • vous allez [] « you go » • en avant [v] « in front »

Word 2 begins with a vowel • LC = {n, z, t (r, p, g)} • Liaison may be unmarked, marked or excluded • LCs normally syllabify with the following vowel (liaison with enchaînement) (Côté, 2002)

Two phonological accounts of liaison • Autosegmental approach (Encrevé, 1988) • Exemplar-based approach (Bybee, 2001)

The autosegmental account (Encrevé, 1988) t i t segmental tier   skeletal tier The liaison consonant is floating with respect to both the skeletal and syllabic tiers O R O R C syllabic tier t i t      O R O R C O R O R A skeletal slot is available that allows the anchoring of LC both to the skeleton and to the syllable tier

The exemplar-based account (Bybee, 2001) • Liaison occurs within grammatical constructionsex.: NOUN – z – [vowel]-ADJPlural • Grammatical constructions range on a continuum from the very general (see above) to the very specific (e.g. c’est-à-dire); this accounts both for false liaisons (overgeneralization of a construction, ex.: chemins de fer [z] anglais) and word-specific differences in the realization of liaison • Grammatical constructions are both storage and processing units

Importantly, liaison consonants do not have a specific status relative to that of the other segments of the construction, in the exemplar-based approach. They are entrenched in the construction and belong to the same plane as the segmental units in the preceding and following words. In the autosegmental approach, by contrast, the characterization of liaison consonants as floating segments provides them with a highly specific status. Consequently, one issue addressed in the present work is whether liaison consonants are processed in the same way as non-liaison consonants.

Processing liaison consonants: previous findings Previous research has focused on the impact of liaison on the recognition of the following word The syllabification of LCs into onset position results in a mismatch between word and syllable boundaries, which may make Word 2 more difficult to identify Ex.: un grand homme [..] « a great man »Do LCs impede W2 recognition? No!LCs may in fact facilitate the identification of Word 2, compared to a baseline condition (Wauquier-Gravelines, 1996; Gaskell et al., 2002; Spinelli et al., 2003)

Processing liaison consonants: previous findings Wauquier-Gravelines (1996) also found that liaison consonants were more difficult to detect by listeners than word-initial consonants in a phoneme-detection task Thus, /n/ was more difficult to detect in un avion « a plane » than in un navire « a boat » Percent of correct detection These results were recently replicated by Hallé (2004)

Wauquier-Gravelines (2005) claims that put together, the word-identification and consonant-detection data provide support for the autosegmental model These data are consistent with the assumption that a specific phonological status is assigned to liaison consonants by the listener Because they are underlyingly floating, LCs do not prevent the onset of Word 2 to be correctly located Flotation may also make them more difficult to detect in the speech chain

Phonetic characteristics of liaison consonants Small phonetic differences may exist in the vicinity of liaison consonants compared to word-initial consonants (eg Delattre, 1940, Dejean de la Bâtie, 1993, Fougeron et al., 2003, Spinelli et al., 2003). This may affect how both types of consonant are perceived by listeners (Gaskell et al.,2002, Spinelli et al., 2003). This is consistent both with the exemplar-based account (fine phonetic detail associated with liaison consonants may be stored in memory) and the autosegmental account (liaison consonants may be phonetically realized in a different way compared to word-initial ones). Note, however, that Wauquier-Gravelines found no significant durational differences in liaison consonants compared to word-initial consonants.

Present work Two perceptual experiments were conducted: • a consonant-detection experiment • a word-identification experiment (gating paradigm) Our main objective was to confirm and extend Wauquier-Gravelines’ findings The phonetic properties of the target consonant were manipulated to examine the listener’s sensitivity to these properties The potentially specific status of liaison consonants compared to fixed consonants in perception was further explored by including fixed word-final and word-medial consonants, as well as word-initial ones

Material 20 sets of four sentences (12 with /z/ and 8 with /n/) The position of the target consonant varied across the sentences in each set as follows

In most cases, liaison consonants appeared in an unmarked context which made their pronunciation obligatory (det + N, monosyll. adv +, adj + N, monosyll. prep. +) In W2-initial and liaison sentences, the target consonant was locally ambiguous and could be interpreted both as a W2-initial and liaison consonant by the listener, eg: • W2-initial: Il y a des [z] (… zéros) • Liaison: J’ai remis des [z] (… écrous)

The target-carrier word was as short as possible: monosyllabic for word-final and liaison targets, mono- or disyllabic for word-initial targets, disyllabic for word-medial targets, monosyllabic • The pre-consonantal and post-consonantal vowels were phonetically matched across the four sentences in each set • The sounds preceding the target consonants were phonetically as different from that target as possible to avoid interference effects • All sentences had about the same number of syllables and the target consonant appeared at approximately the same location in each sentence • The sentences had similar syntactic structures • Word 2 was as semantically unpredictable as possible from the first part of the sentence • 240 filler sentences were also included

Recordings and acoustic measures The material was recorded by a male native speaker of French (5 repetitions for each sentence) Markers were placed at the boundaries of each segment in each V – target cons. – V sequence on the acoustic signal Il rentre à son hôtel [] récupérer sa valise

Average duration of target cons and preceding vowel for /n/ and /z/ in each position • V longer in word-final VC sequences • No difference in /n/ duration depending on position • /z/ longer in word-initial than word-final or liaison position

Manipulating the phonetic characteristics of targets We aimed to assess the perceptual relevance of durational differences in the vicinity of liaison consonants as opposed to word-initial consonants. To do this, the phonetic properties of the target were systematically manipulated. In each set of sentences, the liaison consonant and the preceding vowel were exchanged with the word-initial consonant and preceding vowel.

Two versions of each sentence were created: • In the identity-spliced version (baseline condition), the target C + preceding vowel originated from another repetition of the same sentence: Il rentre à son hôtel []… (target in liaison position) Il rentre à son hôtel []… (same sentence,  repetition) • In the cross-spliced version, the target C + preceding vowel originated from the other sentence of the pair: Il dépasse un nageur []… (target in word-init. position) Elle repasse un habit []… (target in liaison position)

On consultera ton notaire []… (target in W2-initialposition, cross-spliced) The identity-spliced stimuli were used as a baseline condition Il rentre à son hôtel []… (target in W2-initialposition, cross-spliced)

Experimental design • Speeded phoneme detection task • 12 subjects divided into two groups • Two lists of stimuli; for each of the manipulated test sentences, one list contained the identity-spliced version and the other list the cross-spliced version of that sentence • Each group was presented with one of the lists, and therefore heard each sentence once

Main predictions • Liaison consonants will be harder to detect than word-initial consonants • If we assume that listeners are sensitive to fine-grained phonetic differences in liaison consonants compared to word-initial consonants, target detection scores should be lower for cross-spliced stimuli than for identity-spliced stimuli

Results: detection scores • More errors for /n/ than for /z/ (p < .001) • Fewer errors in word-initial position compared to other positions for /z/ • Fewer errors in word-initial than in liaison positionfor /n/ (p < .05)

Results: reaction times (RTs > 250 ms and < 1200 ms only) Longer RTs for /z/ in liaison compared to word-medial position (p < .01)

Results: reaction times (only RTs > 250 ms and < 1200 ms) • Longer RTs for /n/ than for /z/ (p < .001) • No main effect of cross-splicing • No significant interaction between target positionand cross-splicing

Phoneme detection data: summary • As expected, correct-detection scores tended to be higher for word-initial targets than for liaison targets, with word-medial and word-final targets in between • /n/ was more difficult to detect than /z/ in all positions • Cross-splicing had no significant effect on the subjects’ responses, in spite of the durational differences found in liaison consonants compared to word-initial consonants for /z/ • The effect of position and that of cross-splicing may have been minimized for /z/ owing to a ceiling effect (more than 90% of correct detection in all conditions)

Exp. 2: word identification with gating Objective: examine the time course of word recognition in the vicinity of word-initial and liaison consonants • W2-initial: Il y a des [z] (… zéros) • Liaison: J’ai remis des [z] (… écrous) How are local ambiguities in the status of consonants resolved by listeners? Do listeners show a preference for any of the two possible interpretations? Material: 20 pairs of sentences containing word-initial and liaison consonants (/z/: 12 pairs, /n/: 8 pairs; same sentences as in Exp 1)

Each sentence was unveiled to the listener as a series of fragments of increasingly long duration. Il rentre à son hôtel []… • Task: sentence completion • Listeners: 8 native speakers of French

Results: percent responses for each target type Strong tendency for liaison responses to prevail up to the end of the post-consonantal vowel, for both liaison and word-initial consonants

Discussion Exp. 2 showed that listeners tend to categorize locally ambiguous consonants as liaisons (as opposed to word-initial consonants) by default This may be due to the fact that the frequency of occurrence of vowel-initial words is much higher than that of /n/-initial or /z/-initial words. A locally ambiguous consonant is more likely to be a liaison consonant followed by a vowel-initial word than a word-initial consonant. Exp. 1 showed that /n/ is harder to detect in liaison position than in word-initial position. This doesn’t seem to derive from phonetic differences in /n/ depending on position: no significant position-dependent difference in duration was found in the /n/ or preceding vowel, and cross-splicing did not have a significant effect on listeners’ responses

In addition, the lower detection rate for liaison /n/ compared to word-initial /n/ cannot be attributed to a frequency effect. Frequency of occurrence strongly favours liaison. The response patterns in Exp. 2 are consistent with the exemplar-based approach. In this approach, liaison consonants are entrenched in high-frequency constructions, such as DET + N, to which listeners are repeatedly exposed. On perceiving a consonant prior to a vowel at the boundary between two words, listeners may therefore tend to interpret it as a liaison consonant as long as the speech input remains consistent with this interpretation. The autosegmental model is neutral as to how listeners may categorize locally ambiguous consonants.

The response patterns in Exp. 1, however, do not provide support for the exemplar-based approach. In this approach, the liaison consonant does not have a specific status compared to the other segments in constructions. Under the exemplar-based account, liaison /n/ should have been in fact easier to detect than word-initial /n/, since the former is more frequent than the latter in the contexts we used. Exp. 1’s results are in better agreement with the autosegmental model. In this model, liaison consonants are treated as floating segments with respect to the skeleton and syllable tier. They are structurally unstable. This may explain the observed response patterns in Exp 1, since the listeners’ task in this experiment was to explicitly identify a phoneme in the speech chain. The data suggest that liaison consonants may not have the same phonological status as fixed consonants for the listener.

Thank you Work supported by the « Systèmes complexes en SHS » research programme (French Ministry of Research) Thanks are due to Céline Douchez for running Exp. 2

Processing liaison consonants in French: new acoustic and perceptual data