Increasing the mass of partitions in light construction is neither aesthetically pleasing nor cost-effective as a method of sound control. Discontinuous construction methods, however, reduce sound transmission by as much as 6 to 10 dB, with little added cost. A further reduction of 5 to 15 dB is achieved by filling space in walls and floors/ceilings with fiberglass insulation.
Insulation absorbs and dampens sound waves, raising the Sound Transmission Class (STC) rating. As an example, conventionally built walls of wood and drywall have poor STC ratings, generally between 15 and 35. This means normal speech is easily heard
through the walls.
By constructing resilient channels between drywall and studs or joists, and incorporating sound absorbing fiberglass insulation, an STC rating of 55 or better is achieved. An STC rating of 55 or better makes loud speech from an adjoining room inaudible.