Organs deteriorate if you do not use them properly - just as hands and legs are atrophied by disuse and are developed by muscular exercise, etc. There is intimate connection between sight and memory, and between hearing and memory.
He who has acute sight, keen perception, good powers of observation and hearing - he will have a good memory. In the internal astral body there are counterparts of these. They are called astral senses. A yogi hears through astral ears and sees through astral eyes. Thus he can hear sounds from distant lands, he can see objects in distant localities. This is called clairvoyance and clairaudience.
Generally people are very careless. They have no wish to learn higher things and have a fund of knowledge. Keep a watch very close to the ear; hear the sound attentively. On the second day put the watch a little further away. Listen to the tick-tick sound. Every day increase the distance, training yourself to hear the sound. Then plug one ear with the index finger of your hand. Train the ears alternately.
Here is another exercise. Close both ears through yonimudra; try to hear the anahata sounds that emanate from the heart lotus. You will hear ten varieties of sounds, such as: flute, mridanga, veena, conch, bells, thunder, humming of a bee, drum, etc. Allow the organ of hearing (ear) to shift from one sound to another and carefully differentiate the various sounds. Eventually fix the ear on one sound. Try the gross sounds first and then go to the subtle sounds.
There is another exercise. Fix the ears on the pranava dhvani (Om sound) that emanates from a river, ocean or wind. It will be heard like 'bhum' or a long 'Om'. Train your ears to hear this sound. Do this exercise at 4 a.m. or at 9 p.m. when the noise of the town has died down.
Keep your ears keen. Differentiate the sounds of various kinds of birds, beasts, children, factories, motor cars, aeroplanes, cycles, shrieks, yells, snores, sobbing, crying, laughing, mocking, joking, etc.
The mind may be there, the instrument may be perfect, but if the mind is not functioning perfectly, you cannot see or hear properly. Perception is possible only when the mind is linked with the external instrument (ear, eye, etc.).