High environmental noise levels are one of the main reasons for mechanically ventilating buildings. The NAT Vent Attenuator allows this product to be incorporated into the facade of a building such to deal with moderately noisy sites (20 dB Dn,e,w), to sites dominated by noise from motorways or low flying air craft (Dn,e,w 40 dB). The NAT Vent is Attenuator can be tuned to match the frequency characteristics of road traffic and other noise sources. Its flexibility allows the NAT Vent to be installed into a wide range of locations and facades.
Please see Chapter 2 of the MACH Acoustics book.