Nurthish (modern)
Nurthish is high and punctuated with high pitched chirps and pips of their own creation to communicate without their one-time Orrish masters understanding. What little written communication they have are nothing more than drawings of hand-sign, and only serves to communicate up to level 4. Characters without a 4 PER (hearing) suffer a -2 CS in using it/understanding it. It is a languages of the Steel Realms, but it is far from prevalent.
Many Orrish are multilingual, speaking both Orrisha and Nurthish. Nurthish allows them to communicate within their own ranks and their allies in a language not commonly understood or taught outside The Dark Lands and Nurth communities in the Underlands.
Nurth-Hand
All Nurth must learn the Sign of The 2 underground rivers (twined fingers) – it is the universal greeting for them. They communicate silently in the dark by forming their long fingered hands into shapes and pressing them into the palm of the one they are communicating with or carving them in relief backwards for others to “read”. Little deep communication can come of this (maximum level 2); and it is easily hidden on rough walls and nearly invisible to non-Nurth (PER -4 to notice even).