P.5
In addition, airflow used in speech may have either of two direction:
Egressive or air flows out of the vocal tract. That happens when the air pressure inside the vocal tract is greater than the air pressure outside the vocal tract and
Ingressive or air flows into the vocal tract. That happens when the air pressure inside the vocal tract is lower than the air pressure outside the vocal tract.
(ใต้รูป ซ้าย)
Thus, this gives a possible six airstrem mechanisms.
a) Pulmonic Egressive - Used in all human languages.
b) Polmonic Ingressive - Not found in human languages.
c) Velaric Egressive - Not found in human languages.
d) Velaric Ingressive -Used in e.g. Zula (South Africa)
e) Glottalic Egressive - Used in e.g. Navajo (North America)
f) Glottalic Ingressive - Used in e.g. Sidhi (Indonesia)
Velaric Ingressive
Airflow is generated by trapping air inside the oral cavity. This is done by closing the back of the tongue against the velum and the lips or the front of the tongue against the upper teeth/alveolae ridge/palate. By pulling down the body of the tongue, the volume of the enclosed regoin is expanded and a vacuum is create.
Glottalic Egressive
This is the second most frequently used mechanism in the languages in which air contained in the pharynx is used. The air is trapped in the pharynx throung a simultaneous closure of the glottis and a total obstruction elsewhere in the vocal tract. When the larynx moves upwards, the air in the pharynx is compressed, and then expelled by 'releasing' the obstruction.
Glottalic Ingressive
A closure is formed at the vocal flods and at some other point in the vocal tract. The larynx is then lowered causing the air pressure above the larynx to decrease.
Release of the second closure causes the air from outside the body toflow into the vocal tract in order to equalise the pressure.
วันเสาร์ 9:36