Spaced between these seven notes are four semi-tones or komal-svars viz. for re , gā , dhā and ni ; and only one acute-tone or tīvra-svar viz. for mā. The latter, like the chhand called brihati is in the centre of the scale. Added to the pure seven notes the count now becomes twelve and this again reflects the symmetry of the sun-signs.
Here too there are twenty two shrutīs. In terms of music, shruti means the smallest discernible interval of pure sound. These shrutīs can be played on the dhruva veenā, an instrument with twenty two strings, but they are too many shrutīs to sing through the kanṭaḥ or the throat. Thus, all the present day rāgas are based on the selection of seven, six or five notes out of the twelve svars but largely based on the twenty two shrutīs ; each of the svars is constituted of two or three shrutīs. Thus there are thousands of rāgas, each having its own time of singing during the day or night and there are also seasonal rāgas. You are also allowed to go up the scale in one rāga and come down the scale in another. Thus an adept singer can synthesize this movement beautifully in a rendering. And this is called the āröha and the avaröha respectively.