Dictionary of Music - Birding America

chord 75key signatures, which do not necessarily apply tomusic written before 1700 or to much of the musicwritten since about 1910.The key of C major, like all other major keys, hasseven possible diatonic triads, based on each of theseven notes from C to B. Like the scale degrees,these triads are identified by Roman numerals, thesame ones that mark the scale degree of their roots.Thus the triad built on F (the fourth degree in the keyof C) is called a IV chord, that on G (the fifthdegree in the key of C) a V chord, and so on.Chords I, IV, and V all are major triads, II, III, andVI are minor triads, and VII is a diminished triad.(There is no augmented triad in a major scale.)A minor key, such as C minor, has more possiblefig. 59 p/u from p.78triads, since the minor scale includes certain scaledegrees in two forms (for example, in the C-minorscale, both A natural and A-flat and both B naturaland B-flat can be used). Again, various kinds of triadare possible, as shown here:fig. 60 p/u from p.79The notes of a triad need not appear in the conventionalorder, with the root at the bottom. When theydo appear in this arrangement, for example with C asthe lowest note of a C–E–G chord, the triad is said tobe in root position. (The order of the other two notes,E and G, does not affect this terminology, whichdepends entirely on the position of the root, C.) Whenthe third is the lowest note (for example, E–G–C′), thetriad is said to be in the first inversion and is referredto as a 6 3 chord (pronounced “six-three chord”) becausethe upper notes are a sixth and a third above thelowest note of the chord. (It is also called simply asixth chord.) When the fifth is the lowest note (forexample, G–C′–E′), the triad is said to be in thesecond inversion and is referred to as a 6 4 chord (“sixfourchord”) because its upper notes are a sixth and afourth above the lowest note. Another kind of sixthchord is the added sixth, formed simply by adding asixth to a triad, such as A to the triad C–E–G.fig. 61 p/u from p. 79Naturally, not all chords are made up of onlythree notes. In four-part writing for voices or instruments(such as music for soprano, alto, tenor, andbass voices, or a string quartet) the chords mayeither contain more notes than a triad or they may betriads with one of their notes doubled (repeated) inanother octave (for example, C–E–G–C′).If still another third is added above a triad in rootposition, the result is a seventh chord, so calledbecause the highest note is a seventh above the root.Again, there are various kinds of seventh chord,depending on what kinds of interval they contain(major, minor, diminished). Among the most importantare the dominant seventh chord, consisting of a majortriad with a minor third above it (in the key of C major,G–B–D–F), and the diminished seventh chord, adiminished triad with a minor third above it (in the keyof C minor, B–D–F–A). An augmented major seventhchord is an augmented triad (see above) plus amajor seventh; an augmented seventh chord is anaugmented triad plus a minor seventh. With a four-notechord, not two but three inversions are possible, sinceany of the four notes may be used as the root.If a third is added above a seventh chord, a ninthchord results. Similarly, the addition of a third to aninth chord produces an eleventh chord, and stillanother third above an eleventh chord produces athirteenth chord. All of these chords, consisting offive, six, and seven notes respectively, can be inverted.The thirteenth is the largest chord that can be builtfrom thirds, since it contains seven notes. Any additionalnote would simply be a repetition (doubling) ofa note already present in another octave.Chords built up from fourths instead of thirds areknown as fourth chords. (See also FOURTH CHORD;SIXTH CHORD.) In addition, chords may be constructedfrom seconds; these are sometimes called tone clusters.