WHEN FINDING A CORD BY EAR I USED TO FIRST FIND THE ROOT OF THE CHORD OR THE Ist TONE, WHICH IS THE NOTE THAT THE CORD IS NAMED AFTER EX:C USUALLY FOUND IN THE BASS then I would find the 5th ex: in C the 5th is G. Then I would decide if the cord is MAJ or Mi. I would accomplish this by listening to the chord that was being played and play a Maj 3rd in C >E then a Mi 3rd> in C>Eflt.The right E or 3rd would sound good to my ear. This can also be accomplished by finding the root note which sounds good to all the notes of the chord being played. Then try a maj and a mi 3rd to see which sounded best thus making the chord major or minor. This method works well with basic maj and mi cords. It is the method I used to learn songs by ear long before ther were computers and tablature. HOPE THIS HELPS, JIM