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Catia Cucchiarini

Catia Cucchiarini. Quantitative assessment of second language learners’ fluency in read and spontaneous speech Radboud University Nijmegen. Context. Research on automatic assessment of oral proficiency in Dutch as a second language. Fluency.

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Catia Cucchiarini

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  1. Catia Cucchiarini Quantitative assessment of second language learners’ fluency in read and spontaneous speech Radboud University Nijmegen

  2. Context Research on automatic assessment of oral proficiency in Dutch as a second language

  3. Fluency • Important construct in evaluation of second language proficiency • Also relevant for pathological speech

  4. Fluency • Frequently applied notion, but not clearly defined • Various interpretations • Overall language proficiency • Oral command of a language • Temporal aspect of oral proficiency

  5. Two experiments • Exp1: read speech • Exp2: spontaneous speech • Human fluency judgements related to • Objective temporal measures (CSR)

  6. Aim of these experiments To explore the relationship between objective properties of speech and perceived fluency in read and spontaneous speech, with a view to determining whether such quantitative measures can be used to develop objective fluency tests.

  7. Method: speakers Exp1: 60 non-native speakers • 3 proficiency levels • beginner (PL1) • intermediate (PL2) • advanced (PL3) • different mother tongues • different gender

  8. Method: speakers Exp2: 60 non-native speakers • 2 proficiency levels • beginner level (BL) • intermediate level (IL) • different mother tongues • different gender

  9. Method: speech material Exp1: • 2 sets of 5 phonetically rich sentences • read over the telephone

  10. Method: speech material Exp2: existing test of Dutch as a second language (DSL) è Profieltoets • 8 items from BL version • short tasks, 15 s to answer • candidates can answer immediately • 8 items from IL version • long tasks, 30 s to answer • candidates have to reflect to provide motivations

  11. Method: raters Exp1: • 3 phoneticians (PH) • 3 speech therapists (ST1) • 3 speech therapists (ST2) Exp2: • 5 DSL teachers for BL (RBL) • 5 DSL teachers for IL (RIL)

  12. Method: automatic scoring • Speech orthographically transcribed • CSR: 38 monophones + lexicon • Viterbi alignment of speech signals and orthographic transcriptions • Segmentation at phone level

  13. Method: some definitions • silent pause: a stretch of silence of no less than 200 ms • dur1 = duration speech without pauses (s) • dur2 = duration speech with pauses (s)

  14. Method: objective measures Primary variables • art = # phones / dur1 • ros = # phones / dur2 • ptr = 100% * dur1 / dur2 • mlr = mean # phones between 2 pauses • mlp = mean length silent pauses • dsp = tot. dur. sil. pauses / (dur2 / 60) • # sp = # sil. pauses / (dur2 / 60)

  15. Method: objective measures Secondary variables • # fp = # filled pauses / (dur2 / 60) • # disf = # disfluencies / (dur2 / 60)

  16. Method: fluency ratings • Sentences scored on fluency on the basis of a ten-point scale • Raters received no special training

  17. Method: rating procedure • Exp1: each group of raters judged speakers of different proficiency levels • Exp2: each group of raters judged speakers of the same proficiency level

  18. Results: reliability

  19. Results: raw fluency ratings

  20. Results: objective measures

  21. Results: disfluencies • Repetitions: exact repetitions of words • Repairs: corrections • Restarts: repetitions initial parts of words

  22. Results: disfluencies

  23. Results: correlations

  24. Results: correlations

  25. Discussion • Reliable fluency scoring is possible • Fluency scores related to task performed • Role objective variables in rs and ss • similarities: weak relation sec. var. / fluency • differences: varying roles prim. var.

  26. Discussion Read speech: • strong relation: art, ros, ptr, #sp, dsp, mlr • weaker relation: mlp  for perceived fluency pause freq. more important than pause length  two factors important fluency rs: • articulation rate • pause frequency

  27. Discussion Spontaneous speech: • strong relation: ros, ptr, #sp, dsp, mlr • weaker relation: art, mlp  possibly higher freq. pauses effaces importance art  fluency in ss particularly related to var. that contain info on pause freq.

  28. Conclusions • Reliable fluency scoring by human raters is possible • Objective fluency scoring is possible • Fluency scores vary with speech type • Fluency scores vary with task performed

  29. Conclusions • Read speech: fluency scores strongly related to art and pause frequency • Spontaneous speech: fluency scores strongly related to pause frequency and distribution • Expert fluency ratings can be predicted more accurately on the basis of objective measures in rs than in ss

  30. Conclusions • Temporal measures of fluency may be used to develop objective fluency tests • Selection of variables to be employed should be dependent on material investigated and task performed

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