Kef has a "metamaterial" they add to their speaker drivers to absorb specific frequencies in order to modify the frequency response curve of the drivers themselves, as opposed to only trying to correct via the cabinet. https://us.kef.com/pages/metamaterial
I can't find it now, but there was a youtube video of a guy building a fence to block road noise by building interlocking pottery 'bricks' with cavities that would absorb certain frequencies
helmholtz resonators, well known in acoustical engineering, also known as beer bottles and people, enough of which can significantly alter an acoustical signal.
the idea of useing specific shapes to redirect sound is new to me, but parralels how reflected coulor can work in birds and insects, where two mechanisms are employed, pigments that simply absorb(heat up) with some frequencys and reflect others, and then mechanical structures that are tuned to capture some frequencys and reflect others, producing the iridesent effects that are so attractive.
recent work has revealed that silk and artificial cloth's, can convert sound into heat quite effectivly, and other work where transparent plastic is put as an extra sound absorbing layer in windows
You generally want to make sure you're working out specific muscles or muscle groups a certain of times each week and with a certain number of working sets, rather than "I have used $MACHINE recently so I need to do that today."
Ah yes that makes sense! I would think of that as more of a pre-workout filter? Where you select the equipment you have available and it automatically filters out everything that requires equipment you don't have access to.
The feature is definitely not meant to serve as option for what you want to use, but what you can use. You could use it that way, of course, but that's not what it's there for.
Read somewhere a few years ago this was a manufacturer defect and they were in the hook for replacing them all.
I've (not seriously) considered buying a pellet gun to shoot out the 4 massive neon purple lights at the entrance to my quaint 1970s era neighborhood. They didn't remove the old light poles after installing the new ones about 3 years ago, so it's double lit with sodium vapor and purple now.
Curious is there is a single person on the planet that prefers the white (er, purple) street lights?
I don't understand, you prefer the new LED lights but also like reduction in light pollution? The LEDs way brighter, so I'd think you'd prefer older lights.
I'd guess about 20% of the lights in and around Orlando are purple now. Maybe the heat and UV makes it worse here?
As far as directional lighting patterns go, that's a matter of the lamp design. Sodium vapor could be housed in a reflector that directs nearly all of it's light downwards.
I'm not against LED technology being used though, just the rampant failing LEDs and the obnoxious brightness & color they produce. Also not fond of the futuristic looking light pole design they seem to always use.
For astrophotography, sodium vapor's color cast is very easy to filter out, whereas the broad spectrum LEDs are not, especially when they don't all emit the same frequencies.
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