The song was performed by legendary Indian
singer-actor-director-film producer S. P. Balasubrahmanyam, and is
notoriously difficult to master — one section had him singing
non-stop for two minutes.
A.R. Rahman had this to say, "Even SP Balasubrahmanyam, who
is an amazing singer, found it difficult to breathe; so we had to
punch in the vocals at a lot of places. It also is phonetically
sound and very catchy."
http://mothership.sg/2017/07/u-s-choral-group-spontaneously-performs-acclaimed-tamil-song-at-changi-airport-transit-area/
