text: A major feature of the blues scale is the use of blue notes , however , since blue notes are considered alternative inflections , a blues scale may be considered to not fit the traditional definition of a scale . At its most basic , a single version of this `` blues scale '' is commonly used over all changes ( or chords ) in a twelve bar blues progression .
simplified: But , because blues notes ( or blue notes ) have a different form , there can be no one blues scale .