(Excerpted from Noise Control with Concrete Masonry, published by CMACN)
Masonry structures are particularly well suited to the requirements of noise control in multi-family structures. Concrete block masonry wall assemblies provide a density of material with the noise reduction values needed to minimize tenant annoyance and comply with recognized standards. Sound transmission ratings are achieved with masonry construction for the reduction of the noise from freeways, rail movements, and aircraft operations or nearby industrial activity. Sound rated masonry wall systems tested by application of standardized laboratory procedures are available to the architect for combating these exterior noise sources, as well as the undesirable sounds which may be experienced between dwelling units in multi-family construction.
Isolation vs. Insulation
The distinction between isolation and insulation as they relate to the Standards must be emphasized. This important distinction is described as follows:
Isolation of interior spaces from exterior sources is measured by positioning one sound level meter in the room of concern and another directly outside. The difference in the 'A-weighted sound level' measured by each instrument is a direct measure of the isolation provided by the building. The difference depends on that portion of the sound energy which entered the room and was not absorbed by the interior furnishings, carpeting, drapes and walls, as well as the sound transmission loss through the exterior walls, roof, windows, doors and vents.