Silent way to communicate, in brief

ASL

Think of the three-letter abbreviation for the language used by many in the Deaf community.

This clue hints at a quiet method of communication, with "in brief" signaling the answer is an abbreviation. "ASL" stands for American Sign Language, a visual way to converse without sound. The word "silent" directly points to sign language, while "in brief" confirms the short form is needed.