Often a musician will encounter a chord that involves a slight alteration to one of the common chord formulas. The alteration is usually indicated in the name given to the chord. An example of an altered chord would be the Bm7b5 (B minor seven flat five) chord. As its name implies the Bm7b5 chord is a Bm7 chord with the fifth note flattened (1 semitone). The formula for a m7b5 chord is 1 b3 b5 b7.
Thus the notes contained within the Bm7b5 chord are (B D F A). The minor seven flat five is sometimes called the half diminished (N) chord e.g., BN .
Sometimes, when a m7b5 chord is written in sheet music the flat sign (b) is replaced by a - (which also means to flatten a note) e.g., Bm7-5.
Here are the most common root 6, root 5 and root 4 minor seven flat five shapes.
Gm7b5 (Root 6)
Bm7b5 (Root 5)
Em7b5 (Root 4)
Play the following chord progression using a combination of root 6, root 5 and root 4 chords. Use the m7b5 shape that sounds the best for each particular combination.