that the last note is an octave higher than the first note, and the decreasing C major scale is C–B–A–G–F–E–D–[C], with the bracket indicating an octave lower than the first note in the scale. The distance between two successive notes in a scale is called a scale step. The notes of a scale are numbered by their steps from the first degree of the scale. For example, in a C major scale the first note is C, the second D, the third E and so on. Two notes can also be numbered in relation to each other: C and E create an interval of a third (in this case a major third); D and F also create a third (in this case a minor third). Pitch A single scale can be manifested at many different pitch levels. For example, a C major scale can be started at C4 (middle C; see scientific pitch notation) and ascending an octave to C5; or it could be started at C6, ascending an octave to C7. Types of scale Scales may be described according to the number of different pitch classes they contain: Chromatic, or dodecatonic (12 notes per octave) Nonatonic (9 notes per octave): a chromatic variation of the heptatonic blues scale Octatonic (8 notes per octave): used in jazz and modern classical music Heptatonic (7 notes per octave): the most common modern Western scale Hexatonic (6 notes per octave): common in Western folk music Pentatonic (5 notes per octave): the anhemitonic form (lacking semitones) is common in folk music, especially in Asian music; also known as the "black note" scale Tetratonic (4 notes), tritonic (3 notes), and ditonic (2 notes): generally limited to prehistoric ("primitive") music Scales may also be described by their constituent intervals, such as being hemitonic, cohemitonic, or having imperfections. Many music theorists concur that the constituent intervals of a scale have a large role in the cognitive perception of its sonority, or tonal character. "The number of the notes that make up a scale as well as the quality of the intervals between successive notes of the scale help to give the music of a culture area its peculiar sound quality." "The pitch distances or intervals among the notes of a scale tell us more about the sound of the music than does the mere number of tones." Scales may also be described by their symmetry, such as