<Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2016) (Learn how and when to remove this template message) </Td> </Tr> <P> Dhrupad as we know it today is performed by a solo singer or a small number of singers in unison to the beat of the pakhavaj or mridang rather than the tabla . The vocalist is usually accompanied by two tanpuras, the players sitting close behind, with the percussionist at the right of the vocalist . Traditionally the primary instrument used for dhrupad has been the Rudra Veena, but the surbahar and the sursringar have also long been used for this music . Preferably, any instrument used for dhrupad should have a deep bass register and long sustain . </P> <P> Like all Indian classical music, dhrupad is modal and monophonic, with a single melodic line and no chord progression . Each raag has a modal frame - a wealth of micro-tonal ornamentations (gamaka) are typical . </P>

Who modified dhrupad music in hindustani classical music