excercises that can help are....play 2 or 3 notes close together and pick out and sing each individual one, or just listen to 'slow' dissonant music with closely grouped notes and try to focus your ear to pick out each one, then when you can focus your ear, just listen to piano tones individually, you may notice individual qualities in b flat, c sharp, f, etc.... the closest comparison with something else, is the visual sense of colour, you dont think in visual colours when you hear these qualities, but they are just like different feels of vibrancy and mellowness... its very very hard to explain, but if you take in all this, then your on the right track