Acoustics affect critical aspects of a building’s function, from productivity in office settings and performance quality in theaters and auditoriums, to the price an apartment, condominium or single- family house can command. Understanding how to select a combination of building materials, system designs and construction technologies that will provide the most appropriate sound control is key to creating a successful acoustical design. Sound Transmission:
- Airborne sound transmission: Sound traveling through the air and subsequently through partitions and openings.
- Impact sound transmission: Originates by contact with the structure and travels through the structure. Thus, it is governed by a completely different set of values than airborne sound.
Impact Insulation Class (IIC):
A numerical evaluation of a floor/ceiling assembly’s effectiveness in retarding the transmission of impact sound, also determined from laboratory testing. IIC is tested per ASTM E492 and rated per ASTM E989
- ASTM E 492: Standard Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using the Tapping Machine
- ASTM E989: Standard Classification for Determination of Impact Insulation Class (IIC): Determines the rating of floor-ceiling assemblies
While the science behind sound is well understood, using that science to create the desired acoustical quality within a building or room is complex. No single acoustical “solution” can be universally applied to all designs. Each environment features unique parameters the architect and designer must consider when developing floor plans, selecting materials and designing assemblies. Virtually every material—from furniture and wall and floor coverings to computer equipment—will affect sound to some degree. However, designing wall partitions, ceiling systems and floor/ceiling assemblies for the distinct qualities of a space will achieve the most effective sound control.
Sound travels not only in a straight path from its source but also bounces off partitions, bends around barriers and squeezes through small openings, all of which can allow noise to reach surprisingly far beyond its point of origin. Designers must consider the dynamics of sound when determining how they will control noise within a building.