Fig. 1. Organs of speech

There should be distinguished active speech organs, which can be moved into contact with other articulators, such as the tongue, and passive organs of speech, such as the teeth, the hard palate and the alveolar ridge, which are immovable in producing speech sounds.
NB: The learners have to remember four main lip positions in the production of English sounds:
(a) spread, the most typical lip position in the production of English sounds, e.g.: see, meat, sit, set, where lips are slightly spread and pinned to the revealed lower and upper teeth;
(b) neutral (open), i.e. the lips are neither spread nor protruded, though the opening between the teeth is a bit wider than in the spread lip position, e.g.: frog;
(c) rounded (open) as, for instance, in the production of the phoneme /æ/ lips are rounded but they are not protruded, the bulk of the tongue being in its lowest position, e.g.: cat, sat, apple, or the bulk of the tongue is at the back of the mouth cavity as in the production of /ɑ:/ though somewhat advanced;
(d) rounded (close), i.e. the lips are rounded but not protruded, e.g.: moon, look (see Fig.2).

 a)      b)

 c)      d)

Fig. 2. Four main lip positions in the production of English sounds:
a) spread, b) neutral, c) rounded (open), d) rounded (close)