Current Biology found the louder the howler monkey, the smaller his testicles.

A University of Utah researcher co-authored a study released Thursday that reveals size does indeed matter — at least when it comes to howler monkey testicles.

Primatologist Leslie Knapp, professor and chair of the university's Department of Anthropology, found that the smaller a howler monkey's testicles are, the deeper and louder his mating calls.

Overcompensating? Perhaps. The monkeys with the deeper howls also had larger hyoid bones, which enable them to have some of the loudest voices in the animal kingdom, an eardrum-busting call that's been compared to a tiger's roar.

They don't "howl" in the way your dog might, though. Instead, their call sounds more like a non-stop belch.