Concrete is an excellent material for deadening air-borne sound transmission through building partitions. It is particularly useful in multifamily residential construction. This article presents sound transmission class (STC) data obtained from tests of a variety of concrete and concrete masonry walls. These data should satisfy most requirements of the designer of residential and other structures.
For residential construction most codes set an STC value of 45 as the minimum allowable. Values of about 50 are required where living units adjoin public space or service areas. The mass of concrete and concrete masonry walls generally puts them in a range where they have little trouble meeting STC requirements. Other factors that affect sound deadening characteristics are stiffness and the presence of resonant and coincident frequencies.
Because of overlapping of effects of the various factors involved, it is difficult to determine the transmission loss of a particular wall purely by analysis. Consequently most designs rely on STC values determined in the laboratory such as those reported in this article. The STC data given in the table show the performance of a number of test walls with plain or finished surfaces. All walls except one exceeded the minimum STC requirement of 45; all but two exceeded the requirement for 50 for living areas adjacent to public space or service areas; and several were above 60.