Only 1-5 in 10,000 people can do this!

My understanding is that tone languages, like Mandarin, use uniform pitches for their tones, though those pitches can vary by dialect. So all Mandarin speakers from Beijing pronounce their high toned syllables at (maybe) a C.

This means that with interval training, that person could easily develop perfect pitch, because they have an easy reference—they can just pronounce a word with a high tone and know it's a C.