Cross-linguistic Effects in the Perception of Assimilated Speech

1. Cross-linguistic Effects in the Perception of Assimilated Speech Gareth Gaskell, MeghanClayards University of York Oliver Niebuhr, University of Provence

2. Lexical access in speech perception • Rapid identification: 250-500 ms • Large lexicon: 50,000+ words • Crowded space • e.g., “cat” has over 25 neighbours differing on the identity of a single phoneme (e.g., rat, cut, cap) • So, little room for error • Even subphonemic manipulations can affect the activation of a word (Andruski, Blumstein & Burton, 1993; Davis, Marslen-Wilson & Gaskell, 2002)

3. Phonological variation • Problem of crowded space compounded by natural variation in surface form of speech • Focus in particular on assimilation of place of articulation: • Changes place of articulation of word-final coronal consonants to become more like following context • lean bacon  leem bacon • dress shop  dresh shop • Crosses word boundaries • Can be a continuum of assimilation • full assimilation creates strongest ambiguity

4. Contextual Viability • Perceptual system makes use of contextual viability in determining likely underlying sequence • e.g., Gaskell & Marslen-Wilson (1996) • “Leambacon” perceived as “Lean bacon” [shared POA] • But “Leam gammon” causes mismatch in perception [mismatching POA] • Compensation effect observed in a wide range of circumstances (e.g., Gow, 2001; Mitterer & Blomert, 2003)

5. Accounts of compensation • Models that deal with context effect differ in terms of their reliance on statistical learning • Gow (2002, 2003) • separate out cues to assimilated consonant using feature parsing • works best for incomplete assimilation • similar perceptual account given by Mitterer & Blomert (2003) • applies to assimilations irrespective of language background • Gaskell (2003) • learn circumstances of assimilation from statistics of language and compensate accordingly • applies to both complete and incomplete assimilation • predicts cross-linguistic differences (statistics are tailored to native language)

6. Data on cross-linguistic effects • Some studies found little or no effect of native language on perception of assimilation • Gow & Im (2004) – Hungarian/Korean/English • Mitterer et al. (2006) – Hungarian/Dutch • short sequences, simple perceptual tasks • Others found clear effects of language background • Darcy et al., (2007, in press) – French/English • longer sentential context, word detection tasks • Key factor may be the degree to which the full range of utterance processes can be engaged • But with broader sentence context, it becomes harder to control all aspects of stimuli for two sets of speakers • Goal of current research: maintain tight control of stimuli while engaging sentential level processing

7. General Methodology • Speakers of two languages learn an artificial lexicon (words refer to abstract objects) • equates lexical knowledge • During testing, embed same two-word sequences varying on degree of assimilation into sentence contexts using the speaker’s native language • equates sentential context and phonetic properties • Examine lexical preferences using the visual world eye-tracking paradigm • look of evidence of cross-linguistic differences in highly comparable circumstances

8. Choice of assimilation phenomenon • Need assimilation that: • shows significant differences in extent or conditions across two languages • involves consonants that are phonetically similar in the two languages • Selected sibilant assimilation in English and French (cf. Holst & Nolan, 1996) • standard view is that English shows strong regressive alveolar to postalveolar assimilation (e.g., dress shop → dresh shop) • whereas such assimilation is absent in French

9. Phonetic Study Niehbuhr, Clayards, Meunier, Lancia (in revision) 4 speakers of both languages Measured spectral centre of gravity (CoG) and duration

10. Perceptual study - predictions • Language specific contextual compensation should develop in cases where complete assimilation causes ambiguity • Predict cross-linguistic differences in regressive (following context) but not progressive (preceding context) assimilation

11. Experimental Design • Equate Stimuli • Artificial lexicon • 1 French and 1 English native speaker • Listeners hear both speakers in both languages • Compare complete and partial assimilation • cross-spliced intermediate CoG as well as endpoints • Compare following and preceding context /ʃ/ /s/ 1 2 3 4 5 6 7

12. Experimental Design objects buttons cavees caveesh pidas tamash nalip remop samal shamal sival shinnow pagoon pentuf Rendez le nalip shinnow s’il vous plait Render the nalip shinnow please Word 1 Word 2

13. Experimental Design Task from Pirog Revill et. al 2008 Render the nalip shinnow please

14. Experimental Design

15. Testing objects first buttons first Render the caveespagoon please Render the nalip samalplease Following context Preceding context

16. Training

17. Inclusion criteria • Participants with more than 25% errors on endpoints for control condition excluded • Both groups of listeners did better with the French speaker • Main analyses run on just data for French speaker (any bias goes against key prediction)

18. Mouse click responses (following context) /ʃ/ 1 2 3 4 5 6 7 /s/ control shinnow” sival” “Render the cavee... French listeners English listeners Stats (logistic mixed effects model): Effect of test context (s vssh)* Interaction with listener group*** French speaker only

19. Mouse click responses (preceding context) /ʃ/ 1 2 3 4 5 6 7 /s/ control tamash pidas “Render the ...amal” French listeners English listeners Stats (logistic mixed effects model): Effect of test context (s vssh)*** Interaction with listener group(ns) French speaker only

20. Time-course of effects (regressive) English listeners Occulo-motor delay (200 ms) This spectrogram illustrates the control condition (1 sibilant, 120 ms long) step step x following context following context

21. Time-course of effects (progressive) French listeners Occulo-motor delay (200 ms) This spectrogram illustrates one of the test conditions (2 sibilants, 200ms long) preceding context step

22. Conclusions • French and English listeners differ in their use of following context in regressive assimilation • English listeners show contextual viability effects across a broad continuum, including complete assimilations • French listeners show little or no viability effect • In the progressive case, both sets of listeners use sibilant cues contrastively, with no cross-linguistic difference • These data suggest that listeners adapt to the ambiguities typical of their language • Complete assimilation in production leads to compensatory perceptual effects • In other cases, generic feature parsing/compensation for coarticulation applies

23. Thanks to... • Other members of the Marie Curie Sound to Sense group, especially: • Uli Frauenfelder • Sarah Hawkins • Christine Meunier • Noel Nguyen • Eyetrackers: • Gerry Altmann and Dirk Kerzel

25. Phonetic results English French Niehbuhr, Clayards, Meunier, Lancia (in revision)