Yeti

This system of roaring is used by Yetis to communicate between mountain ranges, and has one of the loudest and therefore broadest reach of almost any language. The mountains north of Capital City are often filled with the roar-yodeling, which sounds so similar to the whipping winds and thunderous storms, that it takes a trained ear to distinguish the two.
Yeti is included in the Gether Guide to Languages on DrivethruRPG:
https://www.drivethrurpg.com/product/328473/Gether-Guide-To-Languages