Anahata Nada is literally, the ‘unstruck sound.’ Nada means sound, but it does not refer to the sound that is heard. It is the subtle aspect of sabda (sound). According to Hathayoga, Bhagavan Shiva expounded 10.25 million methods of obtaining samadhi (tranquil meditation) and the practice of listening to Anahata Nada (immanent sound) is said to be the most supreme among them. The sound is heard in the passage of sushumna (a nerve center) when a person sits in a certain yogic posture. This occurs through four stages.
In the
primary stage, the brahma granthi (the knot of Brahma) in he heard is pierced
through pranayama and one experiences a blissful condition in the space at the
heart. The second stage reverberates tinkling sounds (as of ornaments), and the
anahata (unheard) sounds are heard in the space of the heart.
Experiencing
this, one’s body becomes lustrous and fragrant and one enjoys supreme bliss and
hears the sound of a kettle drum. In the third stage, aparicaya (the sound of a
drum) is heard in the space between the two eyebrows. In the fourth stage,
nishpatti, the sound of the flute and the veena (the string instrument) is
heard. Finally, when all sounds cease, one becomes Para Brahman
(Hatha Yoga Pradipika IV. 64-105).