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Rachael-Anne Knight & Mark J. Jones

Plasticity, exemplars, and the perceptual equivalence of ‘defective’ and non-defective /r/ realisations. Rachael-Anne Knight & Mark J. Jones. 1. Introduction. Perception of /r/ stimuli by subjects who use either ‘labiodental /r/’ [ ] or ‘apical /r/’ [] .

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Rachael-Anne Knight & Mark J. Jones

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  1. Plasticity, exemplars, and the perceptual equivalence of ‘defective’ and non-defective /r/ realisations Rachael-Anne Knight & Mark J. Jones

  2. 1. Introduction Perception of /r/ stimuli by subjects who use either ‘labiodental /r/’ [] or ‘apical /r/’ []. No articulatory data here, acoustic terms: • labiodental /r/ = high F3, wide F2-F3 gap. • apical /r/ = low F3, narrow F2-F3 gap. ‘high F3’: F3 = F2 in surrounding vowels Lab r outside articulatory continuum, acoustically distinct.

  3. 2. Developmental data • /r/ mastered late by English speaking children (age 4;5+); • acquisition pathway  >  > , though some data on [] and [] co-occurring; • some adult speakers retain voiced labiodental approximant ; • retention of infantile speech form = non-plasticity. Reasons for this unclear...

  4. 3. Why labiodental /r/? • Research on non-arbitrary relationship between apical /r/ and labiodental /r/. 1) Sound change (actuation, not transmission) 2) Phonology of rhotics 3) Child/clinical phonology 4) Phonetic detail in phonological representations

  5. 3a. Phonetic detail • Research indicates that perception is aided by phonetic detail; • So representation may be detailed; • Frequency of occurrence central: - influences representation - representation influences production • Lab /r/ - point on pathway to development • Not most common - how abstract? why?

  6. 4. Production difficulties • Number of gestures in /r/ (lips, tongue tip, tongue root). • Vocal tract morphology. • BUT [w] > [] is less complex (other reason for this sequence) • WHY tongue tip? • WHY co-occurrence of [] and []?

  7. 5. Perception difficulties • Focus on acquisition of /w/ ~ /r/ contrast. • BUT focus on /w/ - lack of phonetic acuity - [w]-like ≠ /w/. • FURTHERMORE kids with [] have no problem with /r/ contrast. • BUT does seem to explain /w/ in development pathway

  8. 6. Acoustic study • Help to understand [] and []. • 5 subjects, all British English speakers. • Collected formant data (F1, F2 F3) for /r/, /w/ and /v/ at midpoint. • Phonetics of labiodentals - non-lingual, superimposed on contextual lingual gestures. Important to keep same context (here //).

  9. 7. Results 1 • /w/ - as expected - low F1 and F2, high F3. • /v/ - as expected - minor deviation from F values for flanking vowels. • /r/ - 2 patterns seen: a) 4 subjects F2 for /r/ in-between /w/ and /v/; b) 1 subject had F values very similar to /v/. Only b) is TRUE labiodental /r/ (1/5).

  10. 7a. Results 1 /w/ /r/

  11. 7b. Results 1 /v/ /r/

  12. 8. Results 2 • F2 values around 1300 Hz for /r/ for 4 subjects • suggest lingual gesture (but not raised tongue tip because of high F3). • Why 4 subjects have low F2 if this causes perceptual conflict with /w/ in others and is due to (putative) lingual gesture?

  13. 9. Perceptual equivalence? • Mid-frequency F2 equivalent to F2+F3 in apical /r/. • Suggests that ‘labiodental’ /r/ users ignore F3 and match mid-frequency resonance. • ‘Labiodental’ and apical /r/ are perceptually interchangeable (cf. child variation)?

  14. 10. Acoustic relationship F2 in ‘labiodental’ /r/ corresponds to F2 + F3 in apical approximant /r/. Average frequency (Hz) F3 F2 F1 F3 F2 F1 ‘labiodental’ /r/ apical approximant /r/ Category

  15. 11. Perceptual test • Aim was to find out if speakers with labiodental /r/ perceive differently to those with apical /r/ • Decided to construct pairs of VCV stimuli where consonant is some type of rhotic and ask both types of /r/ user whether consonants are same or different

  16. 12. Stimuli • [    ] chosen •  = apical postalveolar approximant • = labialised apical postalveolar approximant •  = labiodental approximant •  = velarised labiodental approximant •  = labial-velar approximant • Recorded 10 tokens of each category • Each token rated for quality and best 2 chosen from each category

  17. 13. Stimuli • Each paired with ‘itself’ in ab (1 and 2) and ba (2 and 1) order • Each token paired with every other in ab and ba order • 80 ‘Different’ pairs presented 3 times (240) • 10 ‘Identical’ pairs presented 24 times (240) • = 480 pairs

  18. 14. Stimuli • Pairs were concatenated in PRAAT • Members of pair 1s apart • ISI of 2s • Each pair proceeded by a beep • Gap of 10 seconds after each 20 pairs • Gap preceded and concluded by 2 beeps • About 45 minutes of stimuli

  19. 15. Subjects • 10 subjects chosen from City and Cambridge student population • 5 with apical /r/ (all female) • 5 with labiodental /r/ (one male) • Paid £5

  20. 16. Instructions You will hear pairs of Vowel-Consonant-Vowel stimuli. Your task is to judge whether the CONSONANTS in the pairs are IDENTICAL or DIFFERENT. Type your response as i (identical) or d (different) in the Excel sheet provided, and press the DOWN ARROW to the next field. If you are unsure whether or not the consonants in the stimuli are IDENTICAL or DIFFERENT, please guess.

  21. 17. Procedure • Subjects were given a practice run of 30 pairs • familiarise subject with task • check volume of recording • Some subjects needed to start the practice several times • After completing the practice, and ensuring instructions understood the test was begun

  22. 18. Overall errors • Lab r users make more errors than apical users • Lab r group = 329 errors (mean = 66) • Apical group = 194 errors (mean = 39) • t(8)=3.4, p<0.05

  23. 19. Errors on ‘different’ pairs • Errors where ‘different’ pairs are labelled as ‘identical’ • Lab r = 199 errors (mean = 40) • Apical = 131 errors (mean = 26) • Note • [ ] • Apicals vs labdentals • [ ]

  24. 20. Errors on identical pairs • Errors where ‘identical’ pairs are labelled as ‘different’ • Lab r = 132 errors (mean = 26) • Apical = 58 errors (mean = 12) • Note velarised labiodental approx

  25. 21. Experiment Conclusions • Labiodental /r/ users, as a group, perform worse than apical /r/ users • Labiodental /r/ users are more variable in their performance than apical /r/ users • Both types of error occur suggesting some of the time subjects are guessing • Lab r users are more likely to think that • apical and labiodental approximants are the same • two velarised labiodental approximants are different

  26. 22. Conclusions • Data suggest that ‘labiodental’ /r/ has a principled relationship with apical /r/ based on mid-frequency resonance. • Phonological representation develops gradually to include more temporal and spectral information: may be (and remain) quite abstract. • Plasticity - Why change? Why fix?

  27. Mark J. Jones Department of Linguistics University of Cambridge markjjones@hotmail.com Rachael-Anne Knight Department of Language and Communication Science City University, London knight@city.ac.uk

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