Transducer For Sound Exciter Dayton Audio Hdn-8 Is Weatherproof. Compact and extremely versatile, the HDN 8 Sound Exciter Transducer lets you create high quality 'hidden speakers' in walls, ceilings, floors, furniture, seating, and virtually any other surface you can think of resulting in great invisible sound. Rugged plastic housing with flat black finish Coarse-threaded mounting stud for single-point mounting into almost any material Hermetically-sealed design for installation in wet or humid environments