A method of reducing sound transmission in a building constructed using horizontal cross laminated timber (CLT) panels to provide a floor of the building and a floor assembly are described. In an implementation, the method includes: attaching a plurality of energy transmission control mounts to a ceiling side of one or more of the cross-laminated timber panels using fasteners; attaching a plurality of furring channels to the energy transmission control mounts; and attaching a cross laminated timber sheet to the plurality of furring channels to form an exposed ceiling layer.