This commonly-used 12-bar Blues variation inserts a secondary dominant A7 (V7/ii) in bar 8 to feed the Dm7 (ii7) in bar 9…
Such secondary dominants are a great way to add harmonic interest and to create a more sophisticated, jazzier sound…
Play along and sing the roots of each chord out loud (Hint: C=Do, D=Re, F=Fa, G=So, A=La). Doing so is an extremely effective and efficient way to do ear training.
Frank playing a real-life example based on the form above…