A list of the perfect & imperfect consonances, and the regular or irregular dissonances Any interval of two simultaneous tones can give a chord. As we have already seen, the intervals can be classified into two different categories: consonances and dissonances. The simple intervals are smaller than an octave and the doubled intervals are larger than an octave. There are also perfect and imperfect consonances. Imperfect consonances include: the minor third, major third, minor sixth and major sixth. The Perfect consonances are: the perfect fourth, perfect fifth, the unison and the perfect octave. The doubled imperfect consonances have the same characteristics: the third becomes a minor tenth, the major third becomes a major tenth, the minor sixth becomes a minor thirteenth and the major sixth becomes a major thirteenth. The doubled perfect consonances adopt the same principle: the perfect fourth becomes a perfect eleventh, the perfect fifth a perfect twelfth, the perfect unison becomes a perfect octave and the perfect octave becomes a perfect double octave. It is the same for the dissonances that make real chords: the minor second, major second, minor seventh and major seventh, but also: the augmented fourth, the diminished fifth, the minor ninth and major ninth. The augmented eleventh is a doubled augmented fourth, the diminished eleventh is a doubled diminished fifth, the minor fifteenth is a doubled minor seventh and the major fifteenth is a doubled major seventh. All these intervals of two sounds are real chords, consonant or dissonant.