Did you know the low frequency performance of Broadway panels can be significantly improved by simply creating an air space behind the panel. By doing so, both sides of the panel are exposed, increasing the overall absorption performance, while the extra depth of a raised panel results in more bass energy being absorbed.

Test results from Riverbank Labs shows the effect of introducing an air space behind Broadway panels. The vertical axis of the graph is the sound absorption coefficient scale. A material with a coefficient of 0 would be 100% reflective and all the sound energy is reflected. A coefficient of 1 would be a material that is 100% absorbent and no sound waves are reflected. The coefficient can go slightly above 1 to indicate a material has thickness and can absorb sound waves from oblique angles so a material with substantial thickness can be more than 100% absorbent.

Graph-1 represents a 2 inch panel surface mounted and with a 2 inch air space. The dashed line represents a 2 inch thick panel mounted directly on the test surface. At 400Hz and above the panel is 100% absorbent meaning no sound waves are reflected back. The double line employs the same panel but mounted with a 2 inch air space behind the panel. The overall performance is boosted over a coefficient of 1 because more surface area is exposed. But the most important effect of adding an air space is that the lowest frequency the panel will absorb has been lowered by 1/3 third of an octave to 315Hz.

This trend will continue as the air space and panel thickness increases. The second graph represents a 3 inch panel surface mounted and with a 3.5 inch air space. The point at which the panel is 100% absorbent is now extended down in frequency to 200Hz, a full octave lower than a 2” panel mounted directly to the wall.

The chart shows bass absorption improves significantly as the air spaced is increased and this trend would continue if the air space in further increased. At some point however the impact of loosing room size is a tradeoff to acoustic performance. Your room size and layout will determine how much of an air space you can install. Raising a panel off the wall is easy. This can be done using wood spacers or with Primacoustic offset impaler clips.