Sound transmission testing simulates the same difficult test
parameters used to determine the performance of firestopping
products. The American Society of Testing and Materials (ASTM)
developed several test standards to determine the acoustical
properties of different products. One of the most frequently utilized
standards is ASTM E-90 Standard Test Method for Laboratory
Measurement of Airborne Sound Transmission Loss of Building
Partitions and Elements. This standard outlines the method and
procedures for measuring sound loss through assemblies and
calculating the overall STC rating. Much like a fire test, the standard
evaluates the performance of the whole system (including the
assembly itself, joints, gaps and penetrations within the assembly)
to measure and determine the Sound Transmission Loss (STL) and
the resulting Sound Transmission Classification (STC) rating. The
method defined by ASM F90 utilizes two separate rooms that are
divided by a partition. The assembly to be tested is installed within
the dividing partition. One of the rooms is designated as the source
room and the other room is designated as the terminating room.
The test apparatus is designed so that sound is only transmitted
through the test specimen.
The purpose of this testing is like the testing conducted during a fire
test. The materials are evaluated to verify that the product system
being installed can maintain the desired rating of the assembly if
an assembly is required to maintain a 2-hour F-rating, then the
materials as installed must be capable of maintaining that rating.
The same is true when STC ratings are required. A separation
wail that is designed to provide an STC rating for example of 50,
then the configuration of materials used to seal openings and joints
must be capable of restoring the separation wall assembly to the
STC rating of 50. Note that an STC rating, like an F-rating, does
not apply to the product itself, but is instead provided for specific
installation of the product in a specific wall construction. Reducing
sound transmission between various occupancies is very important
to the comfort level of the occupants. Architects and engineers are
beginning to incorporate these sound requirements in their projects.