in music, the action of founding the notes in the scale with the voice, or any other given order of musical tones. Intonation may be either true or false, either too high or too low, either too sharp or too flat; and then this word intonation, attended with an epithet, must be understood concerning the manner of performing the notes.

In executing an air, to form the sounds, and preserve the intervals as they are marked with justness and accuracy, is no inconsiderable difficulty, and scarcely practicable, but by the affluence of one common idea, to which, as to their ultimate test, these sounds and intervals must be referred: these common ideas are those of the key, and the mode in which the performer is engaged; and from the word tone, which is sometimes used in a sense almost identical with that of the key, the word intonation may perhaps be derived. It may also be deduced from the word diatonic, as in that scale it is most frequently conversant; a scale which appears most convenient and most natural to the voice. We feel more difficulty in our intonation of such intervals as are greater or lesser than those of the diatonic order; because, in the first case, the glottis and vocal organs are modified by gradations too large; or too complex, in the second.