Near-field Acoustic Metamaterial (NAM)
Near-field Acoustic Metamaterials (NAM) are multi-layers of acoustic metamaterials combined with and inserted around conventional sound absorption materials, such as fiberglass, and acoustic foam – into the spaces between each layer of acoustic metamaterials. This hybrid combination of acoustic metamaterials along with conventional sound absorption materials create the unique near-field acoustic metamaterial (NAM) for broadband noise control. Based on the noise element we are working to overcome we will recommend multiple layers of acoustic metamaterials which may have different membranes, masses or dimensions to produce different vibration patterns under the same frequency sound excitations.
Consequently, high-level sound pressure can be found at the space between the two layers of acoustic metamaterials, which means that high amount of sound energy due to multiply transmissions and reflections of evanescent waves inside NAM is concentrated in the area where the porous material is occupied. The result is that extraordinary sound absorption efficiency can be achieved by using only a thin layer of porous material. Near-field Acoustic Metamaterials offers a compact design and lightweight but possesses capabilities for broadband noise reduction.
The applications for near-field applied metamaterials are our greatest opportunity. Our experience in the aircraft manufacturing industry is extensive. With no requirement for air transfer from one side of the custom barrier to the other (outside the aircraft to the inside) NAM is the perfect solution.
In the healthcare market segment, we believe some equipment is offensive as a result of the noise created. Magnetic Resonance Imaging machines are a potential application of NAM.
In the construction industry, the space occupied by machine operators should not be contaminated by unwanted noise.