MUSIC (Gr, mousike, from mottsu, muse: Let. musica), a combination or succession of sounds having the property of pitch, so arranged as to please the ear. The pleasure derived from music arises from its exciting agreeable sensations, and raising pleasing mental images and emotions. Apart from words, it expresses passion and sentiment, and linked words, it loses its vagueness, and becomes a beautiful illustration of lan guage.
The doctrine of musical sounds is based on the principles of acoustics (q.v.). Sound is conveyed through elastic media by waves, not of alternate elevation and depression; but of alternate condensation and rarefaction; in which it is the form, the condition of the groups of particles that progresses, not each individual particle. When a series of vibrations recur on the ear at precisely equal intervals of time, following each other so closely that each cannot be separately distinguished, the result is a musical sound or note. The sound ceases to have a musical character when each pulsation is individually audible, as is the case when there are fewer than about sixteen beats in a second. The gravity or sharpness of the sound is called its pitch, and depends on the number of vibrations in a given time. A succession or progression of musical sounds following each other constitutes melody; the difference in pitch between any two of them is called an interval. Where two or more musical sounds, whose relative pitch is properly pro portioned, are heard simultaneously, the result is a chord, and a succession of chords constitutes harmony.
When a vibration is communicated to a string stretched between two points, the result is a musical note, whose pitch is dependent on the length of the string and the degree of tension applied to it: the shorter the string, and the greater the tension, the higher is the pitch. If the string be devided in the middle, the tension remaining the, same, the note produced is twice as high in pitch, and is called the octave to the note produced by the whole string. Every vibration of the one corresponds to two of the other. and there is between a note and its octave a far closer relation than between any two other notes; they go together almost as one sound, and are considered to a great extent as one musical sound. In the diatonic scale, familiar to every correct ear, there are six notes, bearing certain harmonic relations to the fundamental note, interposed between it and its octave; and as we ascend, the notes arrange themselves in similar successions of sevens, each set an octave higher, or double the pitch of that which pre ceded it. The seven notes are designated by the names of the first seven letters of the alaphabet, the same letter being used for any note and its octave. For another notation
also in use, see SOLMIZATION. Taking C for the fundamental note, we have for out scale.
The scale may be extended up or down indefinitely, so long as the sounds obtained continue to be musical. The satisfaction and sense of completeness which the diatonic, scale gives the ear, arise from its being founded on correct harmonic principles. The quality called harmony is produced by a coincidence of vibrations; notes are more har monious the oftener their waves coincide. Besides the octave, two of whose waves coincide with one of the fundamental, there are other intervals harmonious, though in a less degree. Dividing our string into three parts instead of two, we have a note higher than the octave, which may be lowered by an octave by making the string two thirds of the original length, and produces a wave of which three coincide with two of the funda mental. Next to the octave, this note stands in the most
relation to the funda mental; it is called the dominant. Dividing the string by five, and lowering the note two octaves, another harmonic is got, called the mediant. In contradistinction from both these, the fundamental note (or any of its octaves) is called the tonic or key-note. C being taken as the key-note, E is the mediant, and G the dominant. These three notes, when struck simultaneously, form the harmonic triad, and stand to each other in the relation of 1, I, (numbers indicating the number of vibrations, which are inversely as the length of the string), or, reducing fractions to integers, in the relation of 4, 5, 6. When a musical string is vibrating, these sounds are heard on close observation more or less distinctly vibrating along with it, the cause being a spontaneous division of the string into aliquot parts, producing subordinate vibrations simultaneously with the principal vibrations. But the dominant may in its turn be the tonic from which another triad of tonic, mcdiaut, and dominant is taken, fOrming -a Seale • of .triads extending int1
• F is the note whose dominant is C (the tonic), and therefore, in respect of C, it is called the suhdonduant. A is the mediant of the subdeminant and therefore called the sub. medians. D is the dominant of the dominant, and is called the super-tonic. B, the mcdiant of the dominant is called the leading note. We have seen that the notes of each triad stand to each other in the relatioa Jf 4, 5, 6. Preserving this proportion, and multiplying to avoid fractions, we have