The chanting of the mantras uses three accents. When a syllable is stressed it is called udaatta , literally meaning acute or high. Then there is anudaatta, which is neither high nor low, it is grave or middle. The latter is indicated in old Vedic texts by a line below the syllable. The last is svarita , which is low. This is marked by a vertical line over the syllable in ancient Vedas and Brahmanas. These accents lead us to the musical notes.
Spaced between these seven notes are four semi-tones or komal-svars viz. for re , ga , dha and ni ; and only one acute-tone or tivra-svar viz. for ma. The latter, like the chhand called brihati is in the center of the scale. Added to the pure seven notes the count now becomes 12 and this reflects the symmetry of the sun-signs.