Alta is a pair of Meso-Cordilleran languages spoken in northern Luzon. As both are primary splits from Proto-South-Central Cordilleran, they are paraphyletic and do not form a subgroup with each other (Reid 2013). Northern Alta language Southern Alta language
References
Austronesian Basic Vocabulary Database, 2008. Reid, Lawrence A. (2013) "Who Are the Philippine Negritos? Evidence from Language." Human Biology: Vol. 85: Iss. 1, Article 15.