Flanking Sound Transmission

Acoustic flanking transmission refers to the indirect path through which sound travels between different spaces or structures, bypassing conventional soundproofing measures.
Understanding flanking transmission is important for effective acoustic design and noise control in buildings and other structures.

Flanking transmission of airborne sound energy is an issue that can occur with stiff acoustic coupling of separations such as walls, floors and facades. The dominant sound transmission path is amplified with all the other flanking paths and in turn, increases the sound transmission to the adjacent room.

For a longer post regarding flanking sound transmission, see this post.