3 ms·
Reading the underlying paper (Ghaffarivardavagh, R., Nikolajczyk, J., Anderson, S., & Zhang, X. (2019). Ultra-open acoustic metamaterial silencer based on Fano-
by hlieberman 7y ago
Reading the underlying paper (Ghaffarivardavagh, R., Nikolajczyk, J., Anderson, S., & Zhang, X. (2019). Ultra-open acoustic metamaterial silencer based on Fano-like interference. Physical Review B, 99(2)), this works on a particular frequency that you can design one of their mufflers for. A 10Hz change to either side of the target drops the effectiveness from 95%+ down to below 50%.
Still very cool, and extremely useful for sources like turbines and HVAC systems that are primarily one or two frequencies, but it's hardly a cone of silence; it won't block out your co-workers anytime soon.
- tensor 7y agoI suppose you could stack several of these on a duct, each designed for a different range, to get more coverage?
- hlieberman 7y agoProbably. Still, it's something to cure fan noise, maybe a couple of harmonics -- not the sort of thing that will work on speech.
- ChuckMcM 7y agoExactly right, just like stacking filters in a signal path. With a 10Hz 3dB point, the bandwidth is 20Hz. Your typical engine exhaust has an acoustic spectrum bandwidth of about 150Hz so a stack of 15 of these would allow you to overlap your filters by 5Hz on either side and notch the entire spectrum out. Depending on how much back pressure it put into the system that could pretty effectively quiet a generator or a turbine.