The aerodynamic voicing constraint
Transglottal pressure drop must exceed 2 cm H2o
- long voiced stops tend to become voiceless
- Dorsal consonants are more likely to be voiceless. Bilabial consonants are more likely to be voiced
- Passive expansion of the vocal tract during voiced stops. Voicing lasts longer with bilabial stops-more vocal tract wall to expand.
Aerodynamic constraint for frication:
Trans-oral pressure drop must be large enough to produce a Reynold’s number above 1700
Intervocalic voiced stops have a greater tendency than voiceless ones to spirantize (become approximants).
Glides and high vowels have a greater tendency to devoice than comparable lower vowels
Epenthetic stops. “Early” closure leads to unintended stops (ohala Speech timing as a tool in phonology)
Vibratory movement of vocal folds under egressive and ingressive airflow. Greater lateral movement under egressive flow.