Finding Sa in a Song ?!

I was asked once by a friend who has learnt western but not carnatic about how i find the Sa in a song, or the scale. I didn't know what to say first because its always been an instinct, never something i could define. It may be easy by indentifying chords but well, I've never done that.

In some cases it'll be very obvious because of the ragam used in the song. But a lot of songs are there where its arguable as to which the Sa is. Some people argue saying its the note that u hit maximum in the song. I thought about it, but that never was how i ever found a Sa( not that i could defend explaining how i did). It confused me in cases only where there was a raga bedham. For example take 'konja neram' from chandramukhi. If u take the starting note as Pa u get valachi, if u take it as Sa u get abhogi ( of course the song is not purely in just this ragam but atleast starts that way). I somehow tended to go with valachi.

Sa can be fixed anywhere in a song. I guess its just the ease with which you extract the other notes compared to it , which decides its place.

When I used to take notes from a song for doing covers for our shows there were songs where in between there used to be scale changes in bgm. I used to take notes in swaram and when this happens, my Sa automatically changes and I would start confusing the hell out of the keyboardist :) For example in 'sundari' from thalapathy in second bgm, there will be a scale change with strings multiple tracks, cello and chorus. Was quite a task getting out the notes for all the tracks. There are loads of songs with such scale changes. I don't think most people ever realize.

I guess all this follows from the same confusion as my western violin classes - "Which is my Sa??" For those who did read that post, am getting better :) But its still swaram for me !!