consecutive intervals decimalization decimation degree diapason diatessaron diatonic interval diatonic semitone enharmonic diesis enharmonic interval fivefold fourth half step halftone interval less semitone melodic interval note octave parallel octaves pentad pentadic pentastyle pentavalent quinary quincuncial quinquefid quinquennial quinquepartite quinquepartition quinquesection quintuple quintuplicate second semitone seventh sextipartition sixth step tenth third tithe tone unison interval whole step