Although it is necessary for this sound that the lips should be closed, and although the air is thus prevented from escaping by the mouth, yet the free passage for the breath by the nose, enables expiration to go on ; and if the nostrils be not stopped, the sound may be continued until the lungs are emptied.
When the nostrils, however, are belch fast, no more air can be forced from the chest than is sufficient to fill the fauces, and consequently the sound can not be prolonged beyond a second or two.
15. The sound expressed by the letter n in the words no, on, and only.
Il•re the expression depends on the cavity of the mouth's being shut, not by the lips, as in the former sound, but by the tongue, which is placed exactly in the same situation as in the pronunciation of the Ilth sound. With this difference, all the remarks that.have just been made with respect to in, apply equally to n.
16. The sound expressed by the letter r in ran, far, around.
In this sound the breath escapes entirely by the mouth. The edge of the tongue on each side is applied to the under surface of the upper grinders and eye-teeth, as in pronoun( ing d; hut the tip, although rendered pretty firm by muscular contraction, instead of being pressed strongly against the roof of the mouth, is merely raised so as to touch gently the part immediately above the in sertion of the incisors. The air is then urged towards this point, sets the tip of the tongue into vibration, and escapes around its edge. On this the expression of r depends.
17. The sound expressed by the letter v in vow, have, aver.
The expression of this sound depends on the under lip being brought slightly over the edges of the upper incisor and eye-teeth, but pressing only on the two middle incisors with such force as to prevent the escape of air. The breath, then, urged forward from the throat entirely into the mouth, escapes between the un der lip and the edges of the lateral incisors and of the eye-teeth.
18. The sound expressed by the letter s in reason and cousin, and by z in zone and lizard.
In this sound the tongue is placed nearly as in the ut terance of the 16th, and the breath escapes entirely be tween its tip and the roof of the mouth immediately above the incisor teeth. The tip of the tongue, however, is
not set into vibration as in that sound, but remains stea dily in one situation, and the air in its passage receives merely a sort of hissing expression.
19. The sound expressed by 8 in pleasure, and by z in azure.
Here the edge of the tongue, on each side, is placed under the inferior surface of the upper grinding teeth ; and its anterior part is so applied to the roof of the mouth, as to leave only a small funnel in the middle, which ter minates behind the incisor teeth in a slight concavity formed by the tip of the tongue. All the breath escapes through this passage.
20. The sound expressed by the letters th in thus, bathing, swathe.
In this sound the margin of the tongue, all round, is placed under the whole of the upper teeth ; but it is held but loosely applied to the edges of the incisors, so that the air, urged forward from the throat, escapes between it and these teeth.
21. The sound expressed by the letters ng in long, gaining.
This is the only Laryngeal sound in our language, in which the breath escapes entirely by the nose. The in stant the nostrils are stopped, the sound ceases. The cause of the expression is easily seen. The velum of the palate is brought a little downwards and forwards, and the posterior part of the tongue a little upwards and backwards; they meet together, and shut up entirely the passage to the mouth.
Oral sounds are such as are not produced in the La rynx, but by some of the parts belonging to the mouth. Like the Laryngeal sounds, they are distinguished from each other by their expression ; but they differ from these, on the other hand, in not being susceptible of the slightest variety of tone. They are only five in num ber.
1. The sound expressed by the letter c, in the words cider, nicer ; by s in sad, asleep, oaks ; by sc in scene ; and by sch in schism and schedule.
This sound depends on the breath being made to pass through the mouth, without having undergone any previous vibration in the larynx, while the tongue is placed precisely as in the pronunciation of the 18th la rynganl sound.