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

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Presentation on theme: "Plasticity, exemplars, and the perceptual equivalence of ‘defective’ and non-defective /r/ realisations Rachael-Anne Knight & Mark J. Jones."— Presentation transcript:

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 /r/ /v/

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

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 Rachael-Anne Knight Department of Language and Communication Science City University, London

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