Dharana is the intense and perfect concentration of the mind upon some interior or exterior object or sound like Anahata sounds, or any abstract idea, accompanied by complete abstraction (Pratyahara) from everything pertaining to the external universe or the world of senses.
Sit in Padma or Siddha Asana. Practise Yoni Mudra by closing the ears with the thumbs. Hear the internal sound through the right ear. The sound which you hear will make you deaf to all external sounds. Having overcome all obstacles, you will enter the Turiya State within 15 days. In the beginning of your practice, you will hear many loud sounds. They gradually increase in pitch and are heard more and more subtly. You should try to distinguish sounds more and more subtle. You may change your concentration from the subtle to the gross, but you should not allow your mind to be diverted from them towards other objects.
The mind having at first concentrated itself on any one sound fixes firmly to that and is absorbed in it. The mind becoming insensible to the external impressions, becomes one with the sound as milk with water and then becomes rapidly absorbed in Chidakasa (the Akasa where Chit prevails). Being indifferent towards all objects, and having controlled the passions, you should, by continual practice, concentrate your attention upon the sound which destroys the mind. Having abandoned all thoughts and being freed from all actions, you should always concentrate your attention on the sound, and then your Chitta becomes absorbed in it. Just as the bee drinking the honey alone does not care for the odour, so the Chitta which is always absorbed in sound, does not long for sensual objects, as it is bound by the sweet smell of Nada and has abandoned its fitting nature. The serpent-Chitta through listening to the Nada is entirely absorbed in it, and becoming unconscious of everything, concentrates itself on the sound. The sound serves the purpose of a sharp goad to control the maddened elephant-Chitta-which roves in the pleasure-garden of the sensual objects.
It serves the purpose of a snare for binding the deer-Chitta. It also serves the purpose of a shore to the ocean-waves of Chitta. The sound proceeding from Pranava, which is Brahman, is of the nature of effulgence; the mind becomes absorbed in it; that is the Supreme Seat of Vishnu. The mind exists so long as there is sound, but with its cessation, there is that state termed Turiya. This sound is absorbed in Brahman and the soundless state is the Supreme Seat. The mind which along with Prana has its Karmic affinities destroyed by the constant concentration upon Nada is absorbed in the unstained One. There is no doubt of it. Being freed from all states and all thoughts whatsoever, you will remain like one dead. You will become a Mukta. There is no doubt about this. The body is certainly like a log and does not feel heat or cold, joy or sorrow. When the spiritual sight becomes fixed without any object to be seen, when the Prana becomes still without any effort, and when the Chitta becomes firm without any support, you become a Brahman (Brahmavid-Brahmaiva Bhavati).
You may experience the tenth sound without the first nine sounds through the initiation of a Guru. In the first stage, the body becomes Chin-chini; in the second, there is the (Bhanjana) breaking or affecting in the body; in the third, there is the (Bhedana) piercing; in the fourth, the head shakes; in the fifth, the palate produces saliva; in the sixth, nectar is attained; in the seventh, the knowledge of the hidden things in the world arises; in the eighth, Paravak is heard; in the ninth, the body becomes invisible and the pure divine eye is developed; in the tenth, you attain the state of Para Brahman. When the Manas is destroyed, when virtues and sins are burnt away, you shine as the Effulgent, Immaculate, Eternal, Stainless, Suddha Brahman.