Spaced Absorbers are self supporting materials that have been designed to provide unique solutions to the absorption versus sound insulation problem.
They utilize the cavity created by mechanically mounting them on the frame to enhance the absorption in lower frequencies by placing an air resistance away from the enclosure walls where the particle velocity is greater than zero.
Filling the cavity can be done for thermal or structural reasons and provided the filler material has low flow resistance perpendicular to the plane of the wall it will also enhance the acoustical performance of the spaced absorber.
Millennium Metal panels are micro cracked to create the ideal airflow resistance to optimally absorb the sound impinging on it. The low frequency absorption can be enhanced by increasing the air space behind it.