As a matter of fact, it now appears to this consortium that the development and maturation of novel noise reduction technologies is hindered by several factors:

  1. An insufficient understanding of the physical mechanisms responsible for the alteration of the flow or acoustic fields. In absence of a phenomenological understanding, theoretical models and numerical simulations can hardly be very successful, preventing thereby optimization of our systems. A key difficulty thereto is the quite complex interlacing of multi-physical phenomena, which cannot be tackled separately as a global comprehension is needed. In that respect, progress is somewhat undermined by the classical engineering education system, where scientific teaching is rather fragmented discipline-wise. As a result, freshly graduated engineers are lacking the multi-disciplinary background that is necessary to tackle these new technologies.
  2. Very tight design constraints are imposed to any novel noise mitigation strategy making its way to the full-scale application: safety, robustness, weight, maintainability, small volume, ecological disposal and naturally cost, are as important concerns, if not more important, as acoustic comfort and compliance with regulations. This imposes quite high thresholds to any novel idea when it comes in competition with already established techniques – thresholds which aren’t sufficiently accounted for in the early research stages. As a result, promising new concepts fail their maturation until the final product stage. Again, a new class of scientists must be trained, more aware of the transversal attributes involved in an industrial innovation process.
  3. In some sectors, there is an insufficient knowledge about the possibilities that are nowadays offered by new materials, new manufacturing techniques such as 3D-printing, recent advances in control systems, etc. These are fast-evolving technological domains; some approaches have already well matured under the impulse of some industrial sectors, which could be beneficial to other applications if more multi-sectorial collaboration platforms were developed.