The hemi anechoic sound chamber designed, engineered and installed by Eckel Industries, Inc. at the Arctic Cat NVH Facility utilizes the EMW (Eckel Metallic Wedge) design for the Chamber’s acoustical treatment or lining. The EMW wedge for the chamber has an overall depth of 27.25 in. with a designed low frequency cut off 120 Hz. The two-peak arrangement on a 2 ft x 2 ft base is constructed of perforated metal with 52% open area. The wedge units are factory finished in white enamel and were mounted to the walls of the chamber using Eckel’s track mounting system.

A double-walled attenuating structure was designed to house the chamber. The outer walled structure was 12 in. thick with staggered studs and two layers of sheet rock on each face. The walls of the two rooms were separated with a 32 in. air space lined with sound absorbing panels. The inner chamber walls were constructed of 12 in. thick concrete block, with all blocks completely filled with mortar or grout for maximum noise reduction and to achieve the specified NC 15 interior ambient noise level.

The pit to house the dynamometer was lined with acoustical panels, so it would not become a resonant cavity once the dynamometer was installed. The entire chamber is constructed on a vibration isolated floor system. A 5000 CFM silenced ventilation system provides the room with ample airflow through roof-mounted silencers and vertical corner inlet and exhausted passages incorporating perforated acoustical treatment.

Two in-swinging wedge cage doors with radius wedges and two out-swinging STC 52 sound doors provide access to the chamber interior working area. Interior dimensions of the chamber are 27 ft 4 in x 31 ft 4 in x 15 ft high wedge tip to wedge tip. Exterior dimensions are 32 ft x 38 ft x 18 ft high.