1. Let the vowel a (as in fate) be sounded.—2. Let it be followed by the consonant p, so as to form the syllable āp. To form the sound of p, it will be found that the lips close on the sound of a, and arrest it. Now, if the lips be left to themselves they will not remain closed on the sound, but will open again; in a slight degree indeed, but in a degree sufficient to cause a kind of vibration, or, at any rate, to allow an escape of the remainder of the current of breath by which the sound was originally formed. To re-open in a slight degree is the natural tendency of the lips in the case exhibited above.
Now, by an effort, let this tendency to re-open be counteracted. Let the remaining current of breath be cut short. We have, then, only this, viz., so much of the syllable āp as can be formed by the closure of the lips. All that portion of it that is caused by their re-opening is deficient. The resulting sound seems truncated, cut short, or incomplete. It is the sound of p, minus the remnant of breath. All of the sound p that is now left is formed, not by the escape of the breath, but by the arrest of it.
The p in āp is a final sound. With initial sounds the case is different. Let the lips be closed, and let an attempt be made to form the syllable pa by suddenly opening them. The sound appears incomplete; but its incompleteness is at the beginning of the sound, and not at the end of it. In the natural course of things there would have been a current of breath preceding, and this current would have given a vibration, now wanting. All the sound that is formed here is formed, not by the arrest of breath, but by the escape of it.
I feel that this account of the mechanism of the apparently simple sound p, labours under all the difficulties
that attend the description of a sound; and for this reason I again request the reader to satisfy himself either of its truth or of its inaccuracy, before he proceeds to the conclusions that will be drawn from it.
The account, however, being recognized, we have in the sound of p, two elements:—
1. That formed by the current of air and the closure of the lips, as in ap. This may be called the sound of breath arrested.
2. That formed by the current of air, and the opening of the lips, as in pa. This may be called the sound of breath escaping.
Now what may be said of p may be said of all the other consonants, the words tongue, teeth, &c., being used instead of lips, according to the case.