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Compensatory coarticulation, /u/-fronting, and sound change in Standard Southern British: an

Compensatory coarticulation, /u/-fronting, and sound change in Standard Southern British: an acoustic and perceptual study.*. Jonathan Harrington, Felicitas Kleber, Ulrich Reubold. * submitted Journal of the Acoustical Society of America. Background.

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Compensatory coarticulation, /u/-fronting, and sound change in Standard Southern British: an

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  1. Compensatory coarticulation, /u/-fronting, and sound change in Standard Southern British: an acoustic and perceptual study.* Jonathan Harrington, Felicitas Kleber, Ulrich Reubold * submitted Journal of the Acoustical Society of America

  2. Background A. Perceptual compensation for coarticulation B. Ohala's model of sound change C. /u/-fronting in SSB General aim of this paper To establish to what extent a sound-change in progress, /u/-fronting in Standard Southern British (SSB) – can be linked to diminished perceptual compensation for coarticulation in Ohala's (1993) model of sound change.

  3. 1. Anticipatory coarticulatory lip-rounding causes spectral centre of gravity lowering in /s/ 2. Listeners know this and reverse its effect (= compensation for coarticulation*) PERCEPTION ACOUSTICS si su si su Listeners reverse the effects of coarticulation Frequency of fricative noise *e.g. Fujisaki & Kunisaki, 1977; Mann & Repp, 1980; A. What is perceptual compensation for coarticulation?

  4. Perceptual compensation for coarticulation s S Frequency of noise If you synthesise a continuum from /s/ to /S/ that can be done by spectral COG lowering and prepend it to a vowel, then listeners are more likely to perceive the SAME synthetic token as /s/ before /u/ than before /a/

  5. s + /a/ + /u/ s s s s s s S s S s S S S Listener compensates for coarticulation (= factors out COG lowering assumed to be attributable to /u/):

  6. B. Cental ideas in Ohala's model of sound change Ohala: "Today's variability is tomorrow's sound change" The origin of many sound changes is not always in the mouth of the speaker, but in the ear of the listener Contra sociolinguists: sound change is not teleological = it's not done on purpose or for any reason, it happens by accident because of an unintended error on the part of the listener (and also for this reason, the origin of sound change is not cognitive nor phonological) Hypoarticulation-induced sound change: one that arises out of the natural processes of coarticulation and in which the listener fails to compensate for coarticulation…

  7. Sound change: /k/ -> /c/ plans /ci, cu/ reconstructs /ci/ plans /ki/ reconstructs /ki/ produces compensates for coarticulation acoustic signal [ci, cu] [ci] [ci] Hypoarticulation-induced sound change in Ohala (the listener thinks: "the speaker meant to say /ci/") Speaker Listener Listener as speaker /c/ has been phonologised because it is planned, produced and perceived, even in contexts that can't be explained by coarticulation

  8. C. /u/-fronting in Standard Southern British /u/-fronting and possible chain-shifting in the Queen's Christmas broadcasts (Harrington, 2008)* ([i] ‘heed’, [] ‘hoard’, [u], ‘who’d’) Harrington (2008), Laboratory Phonology IX, in press Extensive auditory and some acoustic evidence that SSB /u/ has fronted in the last 50 years e.g., Gimson, 1966, Wells 1982, Henton 1983, Deterding 1997, Hawkins & Midgley 2005, Roach, 1997)‏.

  9. Taking into account word-frequency, /u/ frequently (p ≈ 0.7) occurs in a coarticulatory fronting context (e.g. 'you', 'too', 'lose', 'do', 'new'). 1. Speaker produces plans j [j] /ju/  F2 F2-locus target distance u Time This could be just such an example of a hypoarticulation-induced sound change. Why?

  10. locus-target distance F2 Time locus-target distance Decade 2. In an analysis of the Christmas broadcasts at 20 year intervals, the Queen, Harrington (2008)* shows just such a reduction of F2 locus-target distance: * Harrington (2008), Laboratory Phonology 9 in press

  11. /u/-fronting and speech perception [sn] Acoustic input: OLD listeners YOUNG listeners compensate for coarticulation /sun/ /sn/ Perceived as: Our extension of Ohala's model to these data and age-differences in SSB speakers is as follows:

  12. /u/-fronting, speech perception and production (feud) [fjd] /fjd/ [fd] /fd/ compensate for coarticulation sound change /fjud/ [fud] /fud/ (food) PERCEPTION PRODUCTION Front Young Old Back For the Old, the allophones diverge in production, but not in perception (this is the trigger for sound change) For the Young, the allophones are aligned in perception and production and NO compensation for coarticulation

  13. Predictions about age differences PERCEPTION PRODUCTION [fjd] /fjd/ Front Young [fd] /fd/ sound change compensate for coarticulation /fjud/ Old Back [fud] /fud/ Production 1. (trivially) /u/ vowels are fronted for the Young. 2. C-on-/u/ coarticulation is greater in the Old (their /u/ allophones show greater divergence). 3. Young and Old differ primarily on the back allophones (if sound change involves a shift of these to the front). Perception 4. The Old but not the Young compensate perceptually for coarticulation.

  14. Experimental analysis I: Production (Predictions 1 -3)

  15. Method: Speakers 30 Standard Southern British speakers recruited through University of Cambridge and University College London. Subjects were carefully checked to ensure that they were SSB speakers. YOUNG: 14 subjects aged 18-20 (11 F, 3 M)‏ OLD: 13 subjects aged 53-88 (7 F, 9 M) only 1 subject took part in the production study only

  16. Materials Isolated word production of words each produced 10 times Recordings made in U.K. with SpeechRecorder (Draxler & Jänsch, 2004)

  17. Acoustic parameters Formants calculated and F2 was checked and manually corrected. Each F2-trajectory was reduced to a single point in a three-dimensional space formed from the first three coefficients of the discrete-cosine-transformation (Watson & Harrington, 1999; Harrington, 2006; Zahorian, and Jagharghi, 1993) We did this because we wanted to assess vowel fronting in the entire F2-trajectory (from onset to offset) rather than just at the vowel's temporal midpoint (which encodes no dynamic information). Also with the DCT, we avoid having to make an often arbitrary decision about the location of the vowel target.

  18. Discrete-cosine-transformation …at frequency (rad/sample)… …is proportional to the trajectory's: DCT-coeff DCT-0 0 average DCT-1 1 mean linear slope DCT-2 2 curvature decomposes any signal into a set of ½ cycle cosine waves which, if summed, reconstruct entirely the original signal. The amplitudes of these cosine waves are the DCT coefficients. Moreover, the cosine waves at the lowest frequencies encode important properties of the trajectory's shape…

  19. so you can use this technique to smooth formants… F2 (Hz) S y n t h e s i s But the important point for this paper is that each F2 trajectory is reduced to a single point in a 3D-space which encodes a smoothed trajectory, like the one on the right. F2 (Hz) A n a l y s i s DCT coeffs

  20. Quantification of /u/-fronting Log Euclidean distance ratio du = log(E1/E2) = log(E1) – log(E2) So if following hypothesis 1 /u/ is phonetically more back in the Old, then du should be lower for the Old compared with the Young For each speaker separately, we quantified the extent of /u/-fronting in this DCT space by calculating each [u] token's relative distance to the front and back /i/ and /A/ vowel centroids du = 0, [u] equidistant bet. /i/ and /A/ du < 0, [u] nearer /A/ (back) du > 0, [u] nearer /i/ (front)

  21. 2. Quantification of C-on-/u/ perseverative coarticulation used tokens to swoop centroid swoop tokens to used centroid ju ju ju ju used ju ju ju ju DCT-0 ju ju wu wu wu swoop wu wu wu wu wu wu wu DCT-1 If the coarticulatory influences of C-on-/u/ are greater in Older speakers (= hypothesis 2), then 'swoop' (/w/ has a backing influence) and 'used' (/j/ has a fronting influence) will be further apart i.e., the distances between them will be greater than for the Young. We measured separately for each speaker the Inter-Euclidean distance in the DCT space between 'swoop' and 'used'

  22. Hypothesis 3: the age-difference is context-specific i.e., if sound change involves a shift of back allophones towards the front, then Young and Old should differ more on words with a non-front allophone ('food') than those with a front allophone ('feud') We calculated the distance in the DCT-space between Old and Young speakers together separately for each word. Thus the prediction is that the distance between e.g. Old/Young 'food' is expected to be greater than between Old/Young 'feud'.

  23. Results 1: Young speakers have a fronter /u/ F1 x F2 plots at vowel midpoint

  24. Results 1: Young speakers have a fronter /u/ Log Euclidean distance ratio, du Front Back (When du= 0, /u/ is equidistant between /i/ and /A/)

  25. Results 2: a greater C-on-/u/ influence for the Old Averaged, linearly time-normalised F2 trajectories in used and swoop

  26. Results 2: a greater C-on-/u/ influence for the Old Euclidean distance between 'used' and 'swoop'

  27. Results 3: smaller age difference for words where /u/ is in a fronting context Euclidean distance between Young and Old separately per word Yes No C has a fronting effect on /u/? (i.e., the sound change involves a shift of back allophones to the front)

  28. Part II: Speech Perception

  29. A separate group of listeners verified that the endpoints of the continua could be correctly identified. Stimuli randomised and both continua presented in one session 5 times (5 x 13 x 2 = 130 randomised stimuli). Forced-choice identification task: Subjects responded with one of ''used'', ''yeast'', ''swoop'', ''sweep'' to each stimulus. Method: synthetic continua We used HLSYN to create two 13 step synthetic /i-u/ continua at equal Bark intervals by varying F2 in two sets of minimal pairs : (a) /jist/ --- /just/ YEAST---USED (p. tense) (b) /swip/ --- /swup/ SWEEP---SWOOP

  30. Speech perception predictions yeast-used boundary sweep-swoop boundary YOUNG left-shift relative to Old because they have a fronter /u/ u i F2 high F2 low and no (or much less) compensation for coarticulation u i F2 high F2 low OLD u i F2 high F2 low

  31. u i F2 low F2 high u i so the different predicted responses are: 1. WORD: yeast-used boundary left-shifted relative to sweep-swoop (red vs blue) 2. AGE: Young left-shifted relative to Old (dash vs. straight) 3. AGE x WORD Small difference between Young vs. Old on yeast-used (red dash vs. red straight), big difference between Young vs. Old on sweep-swoop (blue dash vs. blue straight).

  32. Results 1: WORD Significantly greater proportion of /u/ responses (across both age groups) in YEAST-USED relative to SWEEP-SWOOP (compatibly with Mann & Repp, 1980).

  33. Results (2)‏: AGE The /i-u/ boundary is significantly left-shifted (greater proportion of /u/ responses) in YOUNG compared with OLD speakers.

  34. Results (3)‏: WORD x AGE Prediction 3. Small difference between YOUNG vs. OLD on yeast-used … big difference between YOUNG vs. OLD on sweep-swoop YOUNG OLD

  35. Discussion I: /u/-fronting and sound-change in terms of Ohala's model. In the 1950-60s. The large phonetic separation between allophones of /u/ in production required coarticulatory compensation to realign them as the same category in perception. For whatever reason, young listeners give up on compensating for coarticulation. They do not attribute [] to context but presume that // (not /u/) was intended by the speaker. Thus, // becomes phonologised... …leading to [] in their own productions even in contexts like 'food', 'move' where it has no coarticulatory explanation.

  36. But which comes first? Ohala: first give up on compensating for coarticulation, then there is a realignment in speech production (= sound change): loss of coarticulatory compensation in perception results in sound change in production. Or perhaps: first there is sound change and then there is a loss of perceptual compensation for coarticulation? This story would be compatible with exemplar theory (Pierrehumbert, 2003) as follows:

  37. /u/-fronting, sound change, exemplar theory 1. /u/ in Standard British English occurs most often (about 70% of the time) after consonants with a high F2 locus ('you', 'too', 'lose', 'do', 'new') 2. According to exemplar theory, this imbalance in lexical and phonological frequency is the trigger for sound change – i.e., the infrequently occurring back [u] in low F2-locus contexts (e.g., 'move', 'swoop') is perceptually unstable and so will be inclined to shift towards the more frequently occurring front allophone []. 3. As this shift occurs in production, there will be less need to compensate for coarticulation in perception, because the allophones will be in progressively closer alignment. So this story has: sound change first, then loss of perceptual compensation.

  38. But in terms of Ohala (1993) it would be unintentional and come about because children are just not as good at compensating for coarticulation perceptually… From the Queen to language acquisition A way forward may be to investigate compensatory coarticulation in young children. Perhaps children learn to compensate for coarticulation relatively late (Ohala, 1993) – perhaps they are more inclined than adults to perceive (incorrectly) an allophone as intended by the speaker. We might then have an alternative explanation for why sound change is so often led by the young. According to the sociolinguistics, this is intentional: the young lead sound change because they want to sound different from their parents/elder generation.

  39. So as usual we need another experiment… Thank you for listening!

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