Karnatakabhashabhushana 7.10.2

7.10.2

akārāntāt śabdāt upamānārthē pōl-pratyayē parē makārāgamō bhavati. vakārasya baśrutiś ca.

After a word ending in the vowel a, when the suffix pōl follows in the sense of comparison, there is the augment of the phoneme m, and the pronunciation of ba for the phoneme va.