Now, there are four semi tones or komal svars viz. for re , ga , dha and ni ; there is one acute tone or tīvra svar viz. for ma. Added to the pure seven notes the count now becomes 12 and this again reflects the symmetry of the sun-signs. All the present day rāgas are based on the selection of 7, 6 or 5 notes out of these 12. And in an Indian classical music composition you can go up the scale in one rāga and come down the scale in another. Here it is called the āröha and the avaröha.
The twelve svars outlined above are based on a finer scale of sounds called the shrutis literally translated as ‘inner sounds’. In the first shlöka of ‘Sangītratnākar’ , a 13th century exposition on music Śarangdeva says :-
brahmgranthi+jamaruta+anugatinā cittain hrtpañkaje
sūrīnām+anu+rañjakah shrutipadam yo ayam svayamrājate
The anāhat chakrā is located in the hrdaya, the heart. anāhat means that which is unbroken. This shlöka says that the ‘life-force’ or prāna – vāyu is like a small tight knot that arises from Brahman, the Unknown. This enters the human body through the nābhi or the navel and rises undifferentiated to the inner core of the heart, the citta. This is the pranava ( p`Nava )  or the collection of shrutis. Interestingly, shruti has two meanings.
Interestingly of the 22 shrutis in the Indian music system  only one name röhinī is common with the names of the lunar constellations . This is in the division of the musical note dhaivat. The lunar constellation röhinī which is now in Taurus was the vernal or spring equinox in 3000 B.C. This shift is due to the precession of the Earth in its orbit around the Sun and this larger circle takes 25200 years to complete. Thus every 900 years approx. the zodiac shifts by one lunar-sign. It takes 2200 years approx. to shift by one Sun-sign. The fundamental note of the musical scale is at present in shadaj but it was not always so. In 3000 B.C. the fundamental note was six shrutis earlier in dhaivat. In fact the name shadaj itself means ‘born of the sixth’ . Thus every 1000 years approx. the traditional vocal music gharānās or families are to correct the fundamental by one shruti to compensate for the precession of the Earth.