Perhaps the greats like Bharata, Sage Matanga and Shaarnga-deva did not know the secret of tuneful tones (up to acceptable level of normal human ear, on the basis of taanpuraa drone) for they do not mention use of drone sound for any of the musical purposes. Most of the practicing musicians knew very well that all the tuneful tones of seven notes could be discovered with the help of the theory of samvaad, in which saa-saa* (*means upper octave), saa-ma and saa-pa play the most crucial role.