Lesson 20 Digitized Smalley a temporary presentation for UF Linguistics students of the audio exercises accompanying William Smalley’s Manual Of Articulatory Phonetics. Some Central Vowels: Vowel Clusters 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18.