10. The sound expressed by the letter b, in boy, rob, above.
In this sound, the velum of the palate is so raised as to shut up completely the orifices leading from the throat to the nose ; the breath, therefore, passes wholly into the mouth. But the expression of the sound depends entirely on the lips being shut; it cannot be pronounced at all with the lips open. Now, as the air which has been excited into vibrations in its passage through the larynx, is afterwards, in this case, urged by the muscles of ex piration. entirely into the mouth, none escaping by the nose ; and, as its escape from the mouth is also prevented by the lips being shut, the mouth must very soon be filled with it. and then, of course, the sound will cease, expira tion being no longer possible. Accordingly, we observe, that the sound of b is one, upon which we can hardly dwell beyond two seconds.
The situation of the tongue does not much affect the expression of this sound, otherwise than in increasing its duration and its hollowness, when placed so as to enlarge the cavity of the mouth, and in producing the reverse effect, when in an opposite position. The sound is also prelongcd, and rendered more hollow, when we permit the inflation of the cheeks, for an obvious reason; but, in general, this inflation is prevented by muscular ac tions, simultaneous with those which shut the lips. The position of the jaws does not modify the expression.
I I. The sound expressed by the letter d, in day, sad, adore.
In this sound, as in the former, the pharyngxal ori fices of the nose ore shut up by the velum of the palate ; and the breath passes all into the mouth. Its ex pi es sion depends, however, on a very different situation of parts. The edge of the tongue t n e ach side is applied close to the under surface t•f the fi,e grinding teeth, and to the inside of the (lc-teeth, and then the tip is press ed firmly against the roof of the mouth, immediately above the insertion of the incisors lu tl is wan, a com pletely close eat ity is form d between the uppt r sin face of the tongue and the palate, which IA rah rs sae the laryi x, and gives it this in collar t pa.s8ion a led d.
Whcli the cavity is filled, the sound, of «torsi:, ceases, as in the case orb.
It is easy to see that this expression cannot be effected by shutting the nostrils, or the lips, nor Ly varying the position ul the Ins cc jaw. When the tip of the tongue, however, instead of being applied to the roof of the mouth, is placed under the edges of the front teeth, a peculiar modification of the expression is produced, which is extremely common in the dialects of some parts of Scot land, particularly in that of Aberdeenshire.
12. The sound expressed by the letter g in good, dog, begone.
In this sound, too, the passage from the throat to the nose is stopped. The back part of the tongue is raised up towards the upper part of the velum of the palate, and is then applied to it so closely as to form a small ca vity with it, opening downwards towards the larynx. Tile air passing into this, receives its expression ; but as the cavity is small, and consequently soon filled, the sound is one of very short duration; considerably shorter than either d or b.
13. The sound expressed by the letter 1 in lay, fail, alone.
litre, also, the breath passes out entirely by the mouth. The tip of the tongue is pressed against the roof of the mouth immediately above the insertion of the incisor teeth ; and the edge of this organ on each side, is applied only loosely to the inner surface of the remaining teeth of the tipper jaw ; so that the air escaping between these teeth and the edges of the tongue, receives the expres sion of 1. The sound cannot be pronounced unless the lips are open.
14. The sound expressed by the letter nz in man, him, amend.
In this sound, the breath is urged alike towards the mouth and the nose ; but it is on that portion of it alone, which is directed towards the mouth, that the expression depends. The tongue lies low, so as to allow a large space for air, between its upper surface, and the roof of the mouth ; the jaws are slightly asunder ; the lips are shut ; and it is the breath pressing against the lips which causes the expression of in.