consecutive intervals decimalization decimation degree diapason diatessaron diatonic interval diatonic semitone enharmonic diesis enharmonic interval fifth fourth half step halftone hexad hexadic hexagonal hexahedral hexamerous hexangular hexapartite hexastyle hexatomic hexavalent interval less semitone melodic interval note octave parallel octaves quinquepartition quinquesection second semitone senary seventh sexennial sextipartite sextipartition sextuple sixfold step tenth third tithe tone unison interval whole step