Tensions are those notes of the scale that are not the notes of the arpeggio, ie the second (2/9), fourth (4/11) and sixth (6/13) note of it.
Depending on the musical context (diatonic or modal harmony) and how we want to use them (as a block in a chord or a melody), tensions may be available or not for each mode of the major scale.
How to know which ones are available and which are not? There is a very simple rule: “available tensions in major harmony are those notes that are at a distance of major second in relation to the notes of the chord” (arpeggio).
Ex1: The Second (2/9) is analyzed with the Tonic (1); the Fourth (4/11) with the Third (3) and the Sixth (6/13) with the Fifth (5).
Following this concept, available tensions for modes in major harmony would be the following:
Applied to harmonic contexts (chords) available notes are those that follow the above rule. In a melodic way non-available notes can be used as passing notes in a melody.
One exception to this rule is when we use modes in modal contexts, in these situations passing notes (not available tensions diatonically), are usually strong notes and features.
I hope you enjoyed another harmonic post. Soon more updates.