Very interesting. It mentions white noise was reduced in a pipe and that the tech is scale-able. That leads me to wonder how/if it works with low frequency energy traveling through the air?
Brian M
Wondering if some of the reduction is about resonance rather than sound reduction? Would have been nice if the device was replaced with a non-active version, to confirm it wasn't just altering some other property of the pipe i.e. not just compared to an open pipe.
i see a number of uses: exhaust mufflers for cars, silencers for guns, air intake noise suppression.
It would be nice to have a quiet vacuum cleaner...
Noise pollution is a huge peeve of mine (first world problem, I know). I look forward to a day when all vehicles are electric and there is a simply way to block out 100% of sound from one's ears to sleep.
guzman, try ear plugs.
The best use would be on jet exhausts. Why have they not tried this yet?
windy, I have. They still let in just enough sound to keep you awake.
Expanded Viewpoint
It sort of looks like those are spiraling channels there, but the picture resolution isn't high enough to be sure. There was a car muffler I heard about from the 1960s called Auger Power, and it had some kind of a spiral baffle inside that reduced noise quite a lot, but didn't restrict the exhaust flow. I never saw one myself, just told about them by a guy I worked with. A couple of years ago my brother got some promo for a muffler with snail shell shaped baffles in it, and they are supposed to have a good tone and have low back pressure. So we built a prototype of a modified design out of some scrap stainless steel sheet metal laying in the back yard, and now need a car to test it out on.
An interesting device. I notice that little detail is given to theory of operation. I suspect that the spiral channels put some of the sound waves into opposite waveforms- a "passive" active noise reduction that cancels out the amplitude.
A truly groundbreaking technology, if it proves out.
It's hard to believe that this device isn't frequency sensitive. I'm guessing it uses a cancellation technique where a sound of a certain wavelength is mixed with an out-of-phase "twin" that cancels it. The twin would be produced by the geometry of the device. In that case I would expect certain other frequencies to be reinforced instead of canceled as the twin being a certain wavelength would arrive in phase and reinforce the tone. However still useful for noise that has a certain constant frequency.