Definition,[f, vj are constrictive fricative, labio-dental; [f] is strong and voiceless, [v] is weak and voiced, in the final position it is partly devoiced.
Articulation.1. The lower lip is very close to the edge of the upper front teeth, thus forming an incomplete obstruction. When the air goes through the narrowing it causes slight friction.
2. For [f] the vocal cords do not vibrate; there may be some
vibration accompanying [vj when it occurs in word initial posi
tions as in vast or between vowels as in never, cover, over.
3. For [f] the air force is very strong.
Recommendations. 1.Start with Articulation Exercise II, 5,