Try this Ear Training Approach!

This technique involves comparing intervals to adjacent intervals against a root note to distinguish their characteristic sounds. I've found the best way to learn how to identify major and minor sounding intervals is to compare them to an adjacent and contrasting interval.

I like to start students off with the 4 major intervals compared to their minor interval counterparts.

Try this exercise in the C major scale using a 6th string root at fret 8: Play the C and D note (which is the major second) on string 5 fret 5 together. Then flat the D to Db (which is a minor second) and note the tonal contrast.

Next, play the root note C along with an E note on string 5 fret 7, notice how bright, happy and refreshing the sound is. Now, flat the major 3rd to the minor 3rd (E flat, one half step lower) this note will sound minor – dark, foreboding, sad. Etc. this effect is amplified by prefacing the minor 3rd with the major 3rd. It's an exercise in contrast.

Next play the C root along with an A note on string 4 fret 6 (this is a major 6th) then flat the A note to Ab (that's a minor 6th) Now play a B note on string 4 fret 9 (that's a major 7th) Then flat the B to Bb (this is a minor 7th).