Music

Today I have a musical question. I am studying classical indian ragas and I keep running across a word "shruti"'. It is defined as "the smallest musical interval that can be perceived by the human ear". But it's not clear to me if that is referring to intervals(like 2nds, 3rds or 5ths ) or to microtones; like shakes, glissandi, etc. Does any of my musical friends with knowledge of this care to share? Ever seeking new knowledge. Thanks the sci wiz. @@@ 

 Sarangi

Sarangi