Despite its importance, many singers lack the discipline to administer ear training exercises to themselves, and rely on their teachers to strengthen their resolve. Often exams are needed to help the music teacher allocate time away from actual singing to this more passive task. It's also easy to neglect because results are long term.

If you want to improve your aural perception (ie singing in tune, singing musically, rhythmically, perceiving tonal colour), try approaching recordings analytically. What instruments are playing? Can you hear the bass guitar line? How many backing vocalists are singing? Is the singer doing their own harmonies? Is the song in a major or minor key? Is the singer using their low register or high voice at a given point?

Sit at the piano and test yourself with intervals. Play middle C. Then sing a perfect 5th or a minor 7th above that, and then play the note on the piano to see if you were right. You should be able to pitch any note within your comfortable voice range once you have been given a point of reference such as middle C.

Make up a tune of about 6 notes on the guitar or piano. Record it on a cassette and write down the order of the notes. Come back 3 days later when you've forgotten the tune and play the tape, and see if you can work out the order of the notes just from listening, then compare your answers with what you wrote down before.

A little bit of regular ear training often is the only way to develop one's musical perceptions, because of the concentration needed and the difficulty of the topic. If performing music was easy, everyone would do it.