N. V. Tatsenko introduction to theoretical phonetics of english

Tongue Frontness/Backness. It is concerned with the part of tongue between the front and the back, which is raised high. From this point of view, the vowel sounds can be classified as front vowels and back vowels. By changing the shape of the tongue we can produce vowels in which a different part of the tongue is the highest point. That means, a vowel having the back of the tongue as the highest point is a back vowel, whereas the one having the front of the tongue as the highest point is called a front vowel. For example: during the articulation of the vowel [u:] the back of the tongue is raised high, so it’s a back vowel. On the other hand, during the articulation of the vowel [ж] the front of the tongue is raised high, therefore, it's a front vowel (see fig. 2.7):


Figure 2.7 - Back and Front Vowels



The Jaws. Some phoneticians consider the jaws as articulators, since we move the lower jaw a lot at the time of speaking. But it should be noted that the jaws are not articulators in the same way as the others. The main reason is that they are incapable of making contact with other articulators by themselves. The lower jaw moves up and down to allow the mouth to open and close. Its movement also helps the tongue move to higher or lower positions, and to makes the space inside the mouth bigger or smaller. All of these movements have a great influence on the sounds we produce.
The Nose and the Nasal Cavity may also be considered as speech organs. It is the space inside the nose where air passes in and out when we breathe through our nose. It can also be called the nasal passage. The sounds which are produced with the nose are called nasal sounds.
In nasal sounds, the velum is lowered to allow airflow through the nasal cavity. In English, nasal consonants are accompanied by the blocking of airflow through the oral cavity. This area is important in producing the nasal sounds [m], [n], and [g]. For these sounds, the air stream moves up and out through the nose instead of the mouth.
The Teeth are also very much helpful in producing various speech sounds. The teeth are used when we say the consonant sounds [f] and [v], with the upper teeth touching the lower lip, and also [9] and [6], with the tip of the tongue touching the upper teeth. The sounds which are made with the tongue touching the teeth are called dental sounds.
Uvula. It functions in tandem with the back of the throat, the palate, and air coming up from the lungs to create a number of guttural and other sounds. In many languages, it closes to prevent air escaping through the nose when making some sounds.