Clairvoyance is vision of distant objects through the inner astral eye or psychic eye. Just as you have physical sense in the physical body, there are astral counterparts of these Senses in the inner, subtle, astral body. The Yogi or the occultist develops these inner organs through practice of concentration. He develops clairvoyant vision. He can see objects in far-off climes. This Siddhi or power is called Dura Drishti (Distant Vision).
Just as light rays penetrate a glass, just as X-rays penetrate solid, opaque objects, so also the Yogi can see the things through a solid wall, can see the contents of a sealed envelope and the contents of a hidden treasure underneath the ground through his inner psychic eye. This psychic eye is the eye of intuition or Divya Drishti or Jnana-Chakshus. One has to develop this inner eye through concentration. Just as the microscope magnifies the small cells, germs, etc., so also he can see things of the astral world very clearly through this inner eye and can magnify them also by special focussing of the inner astral lens.
He creates an astral tube by willing and the strong wishing and thinking and, through this astral tube, he sees things at a distance. The vision may not be very clear in the beginning. Just as the new-born baby learns, so also he learns in the beginning. As he advances in his practice, his inner vision becomes quite distinct. There is another method. The Yogi takes astral journey and sees things during his astral travelling unconsciously.
Just as light rays travel in space, so also astral light rays travel with tremendous velocity. They are caught up by the astral eye. Every one of you has got these astral senses. But few only consciously develop them. A clairvoyant can see the events of the past by looking into the Akasic records and have Trikala Jnana (Knowledge of Past, Present and Future) also. The degree of power varies in different individuals. Advanced clairvoyants are very rare.
Clairaudience is the hearing of distant sounds in the astral plane by means of the astral ear. The process is similar to clairvoyance. The astral sound-vibrations are caught hold of by the astral sense of hearing. A clairvoyant need not necessarily be a clairaudient. These are two distinct powers. Patanjali Maharshi gives the method to develop this power of distant hearing. Shrotrakasayoh (Patanjali Yoga Sutras, 3-41). By Samyama on the relation between the ear and Akasa, comes divine hearing. Samyama is concentration and meditation combined.
All the inhabitants of the Pitriloka (where our ancestors reside) possess this power. Where their descendants perform Sraaddha and Tarpana in this world, they hear these sounds through the power of clairaudience and they are highly pleased. These psychic Siddhis are all by-products of concentration. Just as there are various coal-tar derivatives and various petroleum preparations, so also there are these Siddhis manifest in a Yogi when he concentrates. These are all obstacles in the path of spirituality. The aspirant should ignore them and develop Vairagya. Then only will he be able to reach the goal.
All the sound vibrations of the past are in the Akasic records. The Yogi can hear these sounds nicely. He can hear the sounds of Shakespeare, Johnson, Valmiki, Visvamitra, etc. Just as you can hear now the music and song of a songster who died fifty years ago in the gramophonic records, so also the Yogi can hear the sounds of those persons of the past by concentration connecting his astral hearing to the Akasic records. Just as impressions of your boyhood remain in your brain and the subconscious mind, so also the impressions of old sounds remain in the Akasic records. One should know the Yogis technique only. Just as the experienced record-keeper in the office can bring out in a short time any old record, so also the Yogi can hear the sound of good old days in the twinkling of an eye.
Mind – Its Mysteries and Control by Sri Swami Sivananda