The
non-nasal stops, the fricatives and the affricates from a major class of sounds
called obstruents. Because the airsteam cannot escape through the nose, it is
iether fully obstructed in its passage through the vocal tract, as in non nasal
stops and affricates, or partially obstructed in the production of fricatives.
Obstruents
are distinguished from the major class of sounds called sonorants, sounds that
are produced with relatively free airflow either through the mouth or nose and
which thus have greater acoustic energy than their obstruent counterparts.
Nasal stops are sonorant because although the air is blocked in the mouth, it
continues to resonate and move through the nose. Vowels, lateral/liquids, and
glides are sonorants because the air resonates without being stopped.
Fricatives
are continuant obstruents because although the air is not completely stopped in
its passage through the oral cavity, it is obstructed, causing in the friction
noted above.
Non-nasal
stops and affricates are non-continuants obstruents; there is complete blockage
of the air during the production of these sounds. The closure of a stop is
relased abruptly as opposed to the closure of an affricate, which is relased
gradually, causing friction.
