Foamrite Acoustics

e equipment used, and the formula commonly employed in translating test data to NRC data, have generally produced grossly overstated Noise Reduction Coefficient (NRC) values. These results, which have been published in many product specification sheets, from various manufacturers, over several decades, are very misleading when interpreted strictly in accordance with the NRC definition: ratio of energy absorbed to energy applied. These overstatements are very obvious when certain absorbing panels’ specification sheets boast NRC > 0.9 (near perfect) and some even report NRC > 1 (better than complete absorption). It is my opinion that these overstated NRC values typically report coefficients that represent approximately double the actual transmission losses through the various materials. Nevertheless, we have produced graphs and NRC ratings for several panels in the Foamrite range, using the common formula for reporting NRC. We have generated these reports for comparative interpretation only, so that the Foamrite panels can be fairly compared with NRC reports of other materials produced by competing manufacturers. When interpreting this data supplied by Academy of Sound Engineering, or the NRC data supplied by any report, from any manufacturer, do not interpret this strictly as the portion of incident energy absorbed. Rather use the data only for comparative analysis of one product to another. Though we do not endorse the traditional NRC rating system as a true representation of absorptive characteristics, the graphs provide a very good indication of the absorptive characteristics across the audio spectrum. These will be useful to the architect, or designer, in predicting the effective frequency response of the treatment. Finally, it must be stated that there is no single magic elixir for acoustic treatment or sound proofing. For best results a combination of methods and materials should be employed. We recommend a combination of massive barriers (such as concrete walls), absorptive materials (such as the Foamrite panels), absorptive membranes (such as in the Foamrite Sound Reduction Panel), and some form of diffusion (such as the Foamrite Poly Diffusor panel). This gestalt must also include good airtight seals around all openings, such as windows and doors. (Managing Director – Academy of Sound Engineering)