Syllabic position effects in articulation: Are word-medial and word-final codas equivalent?

Transcription

1 Syllabic position effects in articulation: Are word-medial and word-final codas equivalent? Lisa Davidson New York University 1

2 Syllable position differences Consonant articulations differ depending on whether the consonant is in the traditional onset or coda position of a syllable. Taken as evidence that the syllable has an important status in articulatory coordination. 2

3 Articulatory differences: codas vs. onsets Nasals in coda: larger velar lowering, longer low plateaus (Krakow 1989) /l/ in coda: tongue tip raising gesture follows tongue body gesture; more likely to miss alveolar contact (Browman and Goldstein 1995, Delattre 1971, Gick 1999, Sproat and Fujimura 1993) Stops in coda: weaker, less reliable constriction, greater variability in the amount of contact (Browman and Goldstein 1995, Keating 1995, Keating et al. 1999, Byrd 1996) Fricatives in coda: shorter contact (but not much else) (Byrd 1996, Keating et al. 1999) 3

4 Focus of study Problem with previous research Most studies equate onset with word-initial and coda with word-final Use of monosyllabic words Do word-medial and word-final codas have the same articulatory characteristics? General tongue shape Constriction degree (Constriction duration) 4

5 Predictions Possible that final codas are strengthened (more constricted?) compared to medial codas. Based on Krakow (1989): labial and velic movements in word-final /m/ were longer, more displaced than word-medial coda /m/ 5

6 Duration-based differences If one type of coda has a longer duration, does that correlate with greater constriction? Löfqvist and Gracco (2002): during oral closure, the tongue continues to constrict 6

7 Materials Participants One female (TO) and four male speakers (WE, RE, AR, SH) of American English Stimuli C#C & C.C pairs for /kt/, /gd/, /st/, /zd/ 8 target + 10 filler phrases; read 8 times each in 8 random orders Fairly consistent prosodic pattern for each pair 7

8 Data processing Target frames (extracted with EdgeTrak) /k/ and /g/: most raised and retracted tongue body position during acoustic closure period (before moving toward following /t, d/) /s/ and /z/: frame corresponding to acoustic midpoint of frication Duration measurements: Entire acoustic closure or frication + closure No release between /k/,/t/ or /g/,/d/ /s/ and /z/ measured the same way for consistency 8

9 9 Statistical analysis Smoothing Spline ANOVA (Gu 2002) Spline constructed from mean of 8 repetitions ANOVA determines whether two average curves shapes are significantly different. /s/: Miss Tina vs. mysterious (subj SH) Y

10 SS ANOVA Interaction term indicates the presence/absence of statistical difference Bayesian confidence intervals illustrate where the differences are. Intervals including 0 are not significantly different Interaction effects w/bci for Miss Tina (/s/) Y Y Interaction effects w/bci for mysterious (/s/) X Interaction effects w/bci for myst at time t = X 10

11 Relevant differences For /s/ and /z/: first 3 rd of tongue (blade) For /k/ and /g/: second 3 rd of tongue (body) Which curve is more constricted in this region? /g/: bag dazzled vs. Baghdad (AR) /s/: Miss Tina vs. mysterious (SH) Y

12 Examples /k/: black top vs. blacktop (SH) blacktop (C.C) more constricted

13 Examples /s/: jazz dancer vs. NASDAQ (RE) jazz dancer (C#C) more constricted Y

14 Discussion /s/ is consistent across all speakers Speakers treating /s/ in mysterious as an onset? /s/ in cluster less constricted than singleton? Consistent within speakers (aside from /s/), if there are differences No consistency for coda type across consonants C#C: final coda significantly more constricted C.C: medial coda significantly more constricted --: no difference kt gd zd st AR -- g#d -- s#t SH k.t s#t TO k.t g.d z.d s#t RE -- g#d z#d s#t WE k#t g#d -- s#t 14

15 Results: Duration st kt zd gd General trend: If any difference, medial codas are shorter than final codas (11/20 pairs). Except /s/ for 1618, 1913 (2/20 pairs). 15

16 Duration results When medial coda is significantly shorter than final coda, final coda is not consistently more constricted. 11/20 cases where duration of C#C > C.C Of those 11 cases, only 6 have significantly greater constriction for C#C. 2/11 C.C has greater constriction, 3/11 no significant difference in constriction Duration does not correlate with constriction. Though duration differences are significant, longer Cs may not be long enough to get greater constriction. 16

17 Conclusions Constriction degree of medial vs. final codas is not consistent across consonant types. It is fairly consistent across speakers. Speaker-specific strategies for articulation of medial vs. final consonants? So, can we equate medial and final coda? If speaker-specific differences have acoustic consequences, hearers may use them for identifying or parsing an individual s speech. If not, then differences even consistent ones are like Am. Eng [ ]: they exist, but they don t matter 17

18 Future directions Extend to initial vs. medial onsets Ideally, the full set of comparisons would be carried out to support this conclusion word-initial onsets vs. word-medial onsets initial onsets vs. medial codas medial onsets vs. final codas Etc. Interpreting constriction degree Palate information would help with visualization of the location and degree of constriction 18

19 Acknowledgements Kyung Sin, UCSB, for help in developing the statistical method Serafina Shishkova, NYU, for help in analyzing the data Paul De Decker, NYU, for help in collecting the data. 19