178. The four elements commonly attributed to music (in the order of their development) are: Rhythm, Melody, Harmony, and Timbre (or tone-color).
179. Rhythm is the regular recurrence of accent. In music it is more specifically the regular recurrence of groups of accented and non-accented beats (or pulses)—according to some specified measure-system. Since rhythm implies continuity, there must usually be at least two such measure groups in order to make musical rhythm possible. (See , Sec. 97.)
180. A melody is a succession of single tones of various pitches so arranged that the effect of the whole will be unified, coherent, and pleasing to the ear.
The soprano part of hymn-tunes and other simple harmonized compositions is often referred to as "the melody."
181. Harmony is the science of chord construction and combination.
The term harmony refers to tones sounding simultaneously, i.e., to chords, as differentiated from tones sounding consecutively, as in melody. The word harmony may therefore be applied to any group of tones of different pitches sounded as a chord, although specifically we usually refer to a succession of such chords when we speak of "harmony." It is possible to use the same combination of tones in either melody or harmony; in fact these two elements as applied to modern music have developed together and the style of present-day melody is directly based upon the development that has recently taken place in harmonic construction.
Harmony (as contrasted with counterpoint) first began to be an important factor in music about 1600 A.D., i.e., at the time when opera and oratorio came into existence, when form was established, and when our modern major and minor scales were adopted. Before this practically all music was composed on a contrapuntal basis.
182. Timbre is that peculiar quality of sound which enables one to distinguish a tone produced by one instrument (or voice) from a tone produced by an equal number of vibrations on another instrument.
The word timbre is synonymous with the terms quality of tone, and tone quality (Ger.—Klang-farbe), the excuse for using it being that it expresses adequately in one word an idea that in our language takes at least two: this excuse would disappear (and incidentally a much-mispronounced word would be eliminated) if the single word quality were to be adopted as the equivalent of timbre. Thus, e.g., the soprano voice singing c' has a quality different from the contralto voice singing the same tone.
(The remainder of this chapter and all of Chapter XVIII deal with terms commonly encountered in the study of harmony. Courses in this subject usually begin with a study of scales, but since this subject has already been somewhat extensively treated, this chapter will omit it, and will begin with the next topic in harmony study, viz.—the interval.)
183. An interval is the relation of two tones with regard to pitch. If the two tones are sounded simultaneously the result is an harmonic interval, but if sounded consecutively the result is a melodic interval. Fig. 62 represents the pitches f' and a' as a harmonic interval, while Fig. 63 represents the same pitches arranged as a melodic interval.
184. In classifying intervals two facts should be constantly kept in mind:
(1) The number name of the interval (third, fifth, sixth, etc.), is derived from the order of letters as found in the diatonic scale. Thus the interval C—E is a third because E is the third tone from C (counting C as one) in the diatonic scale. C—G is a fifth because G is the fifth tone above C in the diatonic scale.
It should be noted however that the same number-names apply even though one or both letters of the interval are qualified by sharps, flats, etc. Thus e.g., C—G♯ is still a fifth, as are also C♯—G♭ and C♭—G♯.
(2) In determining the specific name of any interval (perfect fifth, major third, etc.), the half-step and whole-step (often referred to respectively as minor second, and major second) are used as units of measurement.
The half-step is usually defined as "the smallest usable interval between two tones." Thus, C—C♯ is a half-step, as are also B—C, F—G♭, etc.
A whole-step consists of two half-steps. C—D is a whole-step, as are also B♭—C, E—F♯, F♯—G♯, G♭—A♭, etc.
The expressions half-step and whole-step are much to be preferred to half-tone and whole-tone, as being more clear and definite. Thus e.g., the sentence "The two tones are a half-step apart" is much better than "The two tones are a half-tone apart."
185. A prime is the relation between two tones whose pitches are properly represented by the same degree of the staff.
A perfect prime is one whose tones have the same pitch. Middle C sounded by piano and violin at the same time would offer an example.
An augmented prime is one whose second tone is one half-step higher than the first. Ex. C—C♯.
186. A second is the relation between two tones whose pitches are properly represented by adjacent degrees of the staff. (The first line and first space are adjacent degrees, as are also the third line and fourth space.)
A minor second is one comprising one half-step. Ex. B—C.
A major second is one comprising two half-steps. Ex. B—C♯.
An augmented second is one comprising three half-steps. Ex. F—G♯.
187. A third is an interval comprising two seconds.
A diminished third has two minor seconds (i.e., two half-steps). C—E♭♭.
A minor third has one minor and one major second (i.e., three half-steps). C—E♭.
A major third has two major seconds (i.e., four half-steps). C—E.
188. A fourth is an interval comprising three seconds.
A diminished fourth has two minor and one major second. C♯—F.
A perfect fourth has one minor and two major seconds. C—F.
An augmented fourth (tritone) has three major seconds. C—F♯.
189. A fifth is an interval comprising four seconds.
A diminished fifth has two minor and two major seconds. C—G♭.
A perfect fifth has one minor and three major seconds. C—G.
An augmented fifth has four major seconds. C—G♯.
190. A sixth is an interval comprising five seconds.
A minor sixth has two minor and three major seconds. C—A♭.
A major sixth has one minor and four major seconds. C—A.
An augmented sixth has five major seconds. C—A♯.
191. A seventh is an interval comprising six seconds.
A diminished seventh has three minor and three major seconds. C—B♭♭.
A minor seventh has two minor and four major seconds. C—B♭.
A major seventh has one minor and five major seconds. C—B.
192. An octave is an interval comprising seven seconds.
A diminished octave has three minor and four major seconds. C—C♭.
A perfect octave has two minor and five major seconds. C—C.
An augmented octave has one minor and six major seconds. C—C♯.
193. A ninth is usually treated as a second, a tenth as a third, etc. The interval of two octaves is often referred to as a fifteenth.
194. If the major diatonic scale be written and the interval between each tone and the key-tone noted, it will be observed that the intervals are all either major or perfect. See Fig. 64.
In this connection also it will be noted that the interval next smaller than major is always minor, while that next smaller than perfect or minor is always diminished: but that the interval next larger than both major and perfect is augmented.
195. An interval is said to be inverted when the tone originally the upper becomes the lower. Thus C—E, a major third, inverted becomes E—C, a minor sixth.