1. Unit 4 Articulation I.The Stops II.The Fricatives III.The Affricates IV.The Nasals

2. Stops Place –Bilabial /p/ /b/ –Alveolar /t/ /d/ –Velar /k/ /g/ Voicing –Voiced /b/ /d/ /g/ –Voiceless /p/ /t/ /k/

3. Stops: Articulatory manner Sequence 1.Complete VT occlusion 2.Oral pressure positive –~equal to subglottal P –5-10 cm water 3.Rapid VT opening 4.Oral pressure=ambient If Voiceless  Vocal folds abduct  Vocal folds adduct

4. Stops Occlusion and release results in two important feature of stops Acoustic silence, observed during build up of oral pressure Transient, aperiodic sound generated during the release of pressure

5. Stops: VCV time domain

6. vowel burst silent gap/ closure interval voice onset time

7. Stops: characteristic features Silent gap/closure interval Release burst Voice onset time Formant transitions

8. silent gap/closure interval Period during VT occlusion Often absent or reduced in voiced stops Voiced stops have voicing into and often throughout the closure interval How can voicing continue with a closed vocal tract?

9. Silent gap/closure interval voiceless voiced voice bar

10. Stops: characteristic features Silent gap/closure interval Release burst Voice onset time Formant transitions

11. Release burst transient (doesn’t last long) aperiodic (a wide range of frequencies, no harmonic structure) lasts 10-30 msec Often absent when stop is in the final position

12. Release burst

13. Informative about place of articulation Related to the size of cavity in front of constriction Bilabial: diffuse energy dominant in low frequency (500-1500 Hz) Alveolar: diffuse energy that is dominant in higher frequencies (2500-4000 Hz) Velar: compact energy in midrange (1500-4000 Hz)

14. Release burst bilabial alveolar velar

15. Aspiration Observed in voiceless stops Consequence of air turbulence at the open glottis Increases the duration of the release burst

16. Stops: characteristic features Silent gap/closure interval Release burst Voice onset time (VOT) Formant transitions

17. Voice onset time Time between release and onset of phonation Considered to reflect laryngeal/articulatory coordination Is longer for voiceless than voiced stops

18. Voice onset time voiceless voiced

19. Voice onset time For voiced stops, VOT can be Short lag: vocal folds vibrate shortly after release Simultaneous voicing: VOT = 0 since voicing and release are coincident Prevoicing VOT lead: VOT <0 since voicing occurs before release VOT ranges from –20 – 20 msec

20. Voice onset time For voiceless stops, VOT is Termed long lag VOT ranges from 25 – 100 msec

21. Voice onset time Place of articulation is distinguished by VOT Bilabial: relatively short VOT Alveolar: mid-length VOT Velar: relatively long VOT RULE: as the cavity in front of the occlusion gets longer, VOT increases

22. Stops: characteristic features Silent gap/closure interval Release burst Voice onset time Formant transitions

23. Formant Transitions Formants of adjacent vowels will change with VT occlusion Transitions will last about 50 msec (shorter than glides/liquids) Transitions not obvious with voiceless The form of the transition is a function of –The place of articulation –The neighboring sound –F1 and F2 are the key players

24. Formant Transitions Place of articulation Bilabial –F1 starting value: close to 0 Hz –F2 starting value: ~ 600-800 Hz –F1 & F2 will usually rise toward the formants of the adjacent sound

25. Formant transitions: bilabial ah b

26. Formant Transitions Place of articulation Alveolar –F1 starting value: close to 0 Hz –F2 starting value: ~ 1800 Hz –F1 will always rise and F2 will go up or down depending on the preceding and following vowels

27. Formant transitions: alveolar ah d

28. Formant Transitions Place of articulation Velar –F1 starting value: close to 0 Hz –F2 starting value: ~ 1300 Hz when followed by a back vowel ~ 2300 Hz when followed by a front vowel –F1 will always rise and F2 will go down –F3 is helpful with velars, typically the F2-F3 transition is ‘wedge-shaped’ F2 going up, F3 going down

29. Formant transitions: velar ah g

30. Formant transition: voiced vs. voiceless voiceless voiced

31. An important point… When discussing source-filter theory, the sound source was the glottal spectrum When discussing stops (and fricatives and affricates), we introduce a new sound source, noise produced within the oral cavity However, source-filter theory still holds even though the sound source is different…the vocal tract still filters the sound source, whether it is the complex periodic signal from vocal fold vibration, or a transient aperiodic signal produced during a stop release