Adam Buchwald New York University buchwald@nyu 18 June 2009

1. Distinguishing phonetic processing and motor processing:Evidence from instrumental analysis of acquired speech impairment DEPARTMENT OF COMMUNICATIVE SCIENCES AND DISORDERS Adam Buchwald New York University buchwald@nyu.edu 18 June 2009

2. Spoken language production • Producing spoken language requires many levels and processes to be orchestrated • Lexical access in long-term memory; working memory; articulatory planning and implementation • Today: relationship between phonetic planning and motor programming • Guided by discussion of: • Phonetic processing/impairment vs. motor processing/impairment in Apraxia of Speech • Focus on: Consonant clusters

3. Phonetic plans & motor programs • “Phonetic plan” ≡ sound structure representation • includes detail re: temporal overlap of gestures, phasing relations • gestural score in articulatory phonology(Browman & Goldstein, 1986,1988, et seq.) • As in the output of phonetic encoding in some processing accounts(Levelt et al., 1999; Cholin et al., 2004, 2006) • “Motor programs” ≡ detailed representation encoding temporal overlap of articulators • Inter-articulator coordination Are these created by separate systems? What are the properties of impairment to these systems?

4. Consonant clusters • Syllables with onset clusters contain complex structure and phasing • Onset consonants are coupled to vowels (Browman & Goldstein, 1988; Byrd, 1996) • Center of consonant timed to onset of vowel • Complicated by presence of a cluster; in English, center of cluster timed to onset of vowel • Multiple possible ‘repairs’ (or simplifications) • Deletion; changing phasing relation; inserting a vowel Questions regarding 2 different aphasic/apraxic speaker • How are the consonant clusters repaired? • What properties determine the nature of the repair?

5. VBRBuchwald, Rapp & Stone, 2007 • 57, RH, F • Suffered CVA at 51 • large LH fronto-parietal infarct involving posterior frontal lobe, including Broca's area, pre- and post-central gyri and the SMG • Dysfluent spoken production, mainly single-word utterances

6. VBR and schwa insertion • Difficulty producing complex onsets • Produces consonant clusters with a vowel inserted between the two consonants • e.g., bleed [bəlid] • Robust pattern • Occurs with different modalities of presentation (naming, repetition, reading) • What is the nature of these errors? • Epenthesis vs. Articulatory (mis)timing believe

7. Epenthesis vs.Mistiming Epenthesis C1 C2 • Vowel inserted in gestural score Target: C1 C2 target release onset • Gestural mistiming • C1 C2 • Consonant gestures mistimed • Audible release of C1 Open vocal tract ə ə

8. Ultrasound study • Examine articulations to see whether inserted schwa is like lexical schwa • Produce word pairs: bleed-believe • Matched on C1, C2, and stressed V • Compare tongue contours • If epenthesis: inserted schwa = lexical schwa • If mistiming: inserted schwa ≠ lexical schwa

9. Inserted schwa = Lexical schwa Red – Inserted Blue – Lexical Within-category differences EQUAL across-category differences Back Tongue Position Front

10. Consonant cluster repair: schwa epenthesis • The inserted vowel is the result of epenthesis • Articulatory data from ultrasound: tongue contour of inserted vowel similar to lexical vowel • Similar variability between vowels and within vowel types • Supported by acoustic data (duration, variability, co-articulation) • Systematic epenthesis repair of obstruent-sonorant clusters • Removes structural (and articulatory) complexity by adding schwa to phonetic plan

11. DLEBuchwald, Rapp & Miozzo, 2009 • 72 year old aphasic/apraxic speaker • Spoken production limited – short phrases; labored • Produces systematic consonant cluster errors in deletion of /s/ from /s/-stop and /s/-nasal clusters • Question: at what level does deletion take place? • Is deletion part of phonetic plan or does it occur during generation of motor program? steer deer tier smash mash

12. Phonetic errors vs. motor errors • Phonetic planning precedes motor programming • If phonetic plan has no /s/, then the token has singleton onset consonant and should be produced accordingly • If phonetic plan has /s/ and deletion occurs at motor level, then timing should be appropriate for cluster • Compare tokens with deleted /s/ to singletons • Use acoustic properties of language to help with this • /s/-stops: VOT in spin is closer to binthan pin • /s/-nasals: nasal duration in snail shorter than nasal in nail • Paired comparisons of target clusters with singletons • e.g., speak vs. peak, beak • e.g., smash vs. mash

13. Hypotheses • Phonetic planning errors • Stops in deletions more similar to singleton voiceless stops • Reflects /s/ being absent from phonetic plan • Nasals in deletions same duration as singleton nasals • Reflects /s/ being absent from phonetic plan • Motor programming errors • Stops in deletions more similar to singleton voiced stops • Reflects /s/ being absent from phonetic plan • Nasals in deletions shorter than singleton nasals • Reflects /s/ being absent from phonetic plan

14. /s/-stop and singleton stop VOT Alveolar Labial • What factors increase the likelihood of repair? Velar

15. /s/-nasal duration • Nasal duration and VOT both reflect the production of a phonetic plan generated without an /s/

16. Phonetic planning errors • These two cases of apraxia both exhibit phonetic planning errors • Does not mean these are the only possible errors; just happens to be the case here • What to do with these errors? • Examine factors that influence the incidence and nature of these errors to learn about phonetic planning system • For each individual, we see effects of (relatively abstract) phonological representations on their errors

17. Phonological effects: VBR • VBR: epenthesis errors in obstruent-sonorant clusters • Words with C/j/ onset (e.g., cute) argued to have complex vocalic diphthong (/ju/) rather than cluster • If #Cw sequences (as in queen, quote) are clusters: • Should be repaired via epenthesis • If #Cj as in cute, music are clusters: • Should be repaired via epenthesis, as other clusters • Never repaired via epenthesis • Repaired via deletion: /kjut/  [kut] cute music

18. Phonological effects: DLE • DLE: /s/-deletion in obstruent-obstruent and obstruent-nasal clusters • English has a few other obstruent-obstruent and obstruent-nasal onsets (/∫/-initial) • If DLE’s ‘repair’ can be expressed over natural classes, should similarly affect these sequences • In addition, other sonority-based descriptions affect error rate – deletion very rare in /sl/ and /∫r/ clusters

19. Summary and future directions • Instrumental analyses of apraxic/aphasic speech can show errors of phonetic planning • Phonetic planning errors appear to be affected by phonological properties, leading to systematic sound structure repairs • Future work • Explore error systematicity as a way to determine whether errors • Extend analyses to other impairments, particularly motor programming impairment and children with speech sound impairments (with HBK, CR) • Incorporate other speech production instruments (EMMA? Real-time MRI?)

20. Brenda Rapp Maureen Stone Michele Miozzo Paul Smolensky Acknowledgements VBR DLE Cettina Chiarelli Cristina Sanchez