Acoustic imaging method development
In order to reduce aircraft and wind turbine noise, acoustic imaging works on localizing the sound. There are a lot of methods, that are all application dependent. But this is not a simple task. An aircraft is a very complicated sound source as we have the landing gear, the engines and the wings. Each of these sources meet in a different way. With the devices designed doing research at acoustic imaging, we can isolate the contribution of each of these sources.
Adding value
Using acoustic imaging devices, the angle in the end is to improve the noise prediction models. Improving simple models that only give one noise level, provides the opportunity to spot a large variability of this level that are not yet explained. dr. Roberto Merino Martinez explains one of the benefits of this distinction: “One of the coolest findings of my PhD was about the landing gear of the planes. Normally, you have some cavities. When you have wind on it, they behave like a flute: they whistle. This is a very tonal sound, that is really annoying compared to a lower engine sound. Something simple as closing those cavities can thus reduce how people complain. In the end, losses are made when people complain.”.
Once we know how the noise is, we can reduce it by some noise reduction method.
In general, we’re applying this to aircraft and wind turbines but you can apply this to trans, cars, anything that makes noise.
Future Work
Research never ends. Roberto Merino Martinez already has plans for further research. The big problem of noise is that it is annoying. However, different sounds, even if you have the same decibel, can vary in how annoying it is. The decibel unit is just how much pressure a wave has. “So we are working on trying to quantify on how annoying sound is. Then you can focus not on the loudest part but on the most annoying part.”
For more information about this topic, you can contact Dr. R. (Roberto) Merino Martinez or S. (Salil) Luesutthiviboon