Interior Design Professional Practice Exam

Answer: C - The Sound transmission class (STC) is used to evaluate the acoustical quality of a space or a material.

Sound transmission class (STC) is a rating of sound isolation of building wall assembly. A higher STC means better sound isolation,  STC is commonly used to rate interior partitions, ceilings/floors, doors, and windows. The STC rating figure represents approximately the decibel reduction in noise that the assembly can provide.