Anahata sounds (or the melody) are the mystic sounds heard by the Yogi at the beginning of his cycle of meditation. This subject is termed Nada-Anusandhana or an enquiry into the mystic sounds. This is a sign of purification of the Nadis or astral currents, due to Pranayama. The sounds can also be heard after the uttering of the Ajapa Gayatri Mantra, "Hamsah Soham," a lakh of times. The sounds are heard through the right ear with or without closing the ears. The sounds are distinct when heard through closed ears. The ears can be closed by introducing the two thumbs into the ears through the process of Yoni Mudra. Sit in Padma or Siddha Asana, close the ears with right and left thumbs, and hear the sounds very attentively. Occasionally, you can hear the sounds through the left ear also. Practise to hear from the right ear only. Why do you hear through the right ear only or hear distinctly through the right ear? Because of the solar Nadi (Pingala) which is on the right side of the nose. The Anahata sound is also called Omkara Dhvani. It is due to the vibration of Prana in the heart.
TEN KINDS OF SOUNDS
Nada that is heard is of 10 kinds. The first is Chini (like the sound of the word Chini); the second is Chini-Chini; the third is the sound of bell; the fourth is that of conch; the fifth is that of Tantri (lute); the sixth is that of Tala (cymbals); the seventh is that of flute; the eighth is that of Bheri (drum); the ninth is that of Mridanga (double drum) and the tenth is that of clouds, viz., thunder.
Before thou settest the foot upon the ladder's upper rung, the ladder of the mystic sounds, thou hast to hear the voice of thy inner God (Highest Self) in 7 manners. The first is like the nightingale's sweet voice chanting a song of parting to its mate. The second comes as the sound of a silver cymbal of the Dhyanis, awakening the twinkling stars. The next is as the melodious plaint of the ocean-sprite imprisoned in its shell. And that is followed by the chant of Veena. The fifth sound of bamboo-flute shrills in thine ear. It changes next into a trumpet-blast. The last vibrates like the dull rumbling of a thunder-cloud. The seventh swallows all the other sounds. They die, and then are heard no more.