New acoustic insulation meta-material technology for aerospace
Sound pressure level in aircraft cabin are similar to a noisy work place. One of the most disturbing noise for passengers is related to the engine fan noise during take-off and approach. This noise is mainly tonal (i.e., at specific frequencies) and in the low frequency range (below 500 Hz) – see figure below. Reducing this noise for the comfort of passengers is an important and challenging issue in aeronautics. One way to reduce cabin noise is to use efficient thermal acoustic insulation blankets between the interior trim panel and the exterior shell. However, conventional acoustic materials (ex.: glass wools, foams) have reached their limits in terms of sound proofing, and non-conventional ones, such as metamaterials, need to be industrialized.