Flanking transmission

Flanking transmission, also known as noise flanking, a flanking path, or indirect sound transmission, is the transmission of sound between spaces through indirect pathways within a building that bypass the primary separating element, such as a wall, floor, or ceiling. In architectural acoustics, sound may travel through connected structural elements, gaps, ductwork, pipes, ceilings, floors, or other parts of a building, reducing the effectiveness of a partition's intended sound insulation.

The significance of flanking transmission depends on the design and construction details of the building and is an important consideration in acoustic design and noise control engineering. Several methods have been developed to predict the apparent sound reduction index of building constructions. Established prediction models are generally reliable for heavy, homogeneous, and isotropic structures, but are less suitable for lightweight constructions, whose critical frequencies often fall within or above the frequency range of interest.