The mission of Tanpuras in Yoga is Satsang by using the technique of Kharaj.
Kharaj is a vocal technique used by Dhrupad singers. Start inhaling normally through both nostrils. Breath out and touch the sound directly without letting air touching the sound and sing the sound A (akar). Akar comes from the word a-karma This approach allows a deeper exploration of the voice: a steady, grounded and open voice. After doing akar for a while, you will discover what one single note can bring to you. You will understand much more the next note.
<< Let the sound A be of the nature of ultimate reality without qualities, and the essence of all things. It is the sound that illuminates >>. (Nandiskesvara Kasika)