Surface or corner applied porous materials lose efficiency at
low frequencies,because the particle velocity or air movement
associated with these long wavelengths is low. The Modex™
Broadband consists of a freely moving steel plate 1 x 1.5 m
sandwiched between porous layers . Both react together in a
mass-spring manner offering absorption via three mechanisms.
First,the metal plate provides pistonic absorption down
to 63 Hz by vibrating against the “spring” of the porous backing.
Second,the bending modes of the free-moving plate are
heavily damped by the proprietary adhesive coupling with the
porous backing up to about 125 Hz. Lastly,mid-frequency
sound waves diffract around the plate’s edges to be propagated
and thus dissipated in the deep passive porous absorber layer.
Together,these mechanisms offer the industry’s first truly efficient,
broad bandwidth low frequency absorber with a shallow
profile of only 4 inches.
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