4 ms·
Everything is a microphone?
by sytse 9y ago
Everything is a microphone?
- frabert 9y agoEvery speaker is a microphone
- amelius 9y agoWell, so is a bag of chips. That doesn't explain the bad choice of title.
- nayuki 9y agoThe original research in 2014 is presented well. This article in 2018 butchers the terminology, using "speaker" instead of "microphone".
- GuiA 9y agoSpeakers and microphones are both transducers, which is what the author seems to be getting at.
- lostmsu 9y agoBut leafs shake because they receive waves. Not the other way around.
- deleted 9y ago[deleted]
- CPLX 9y agoAnother valid metaphor though is that video of the leaves can be decoded the same way video of a speaker would. The analogy works either way.
- nkoren 9y agoYup. Interestingly, actual speakers work either way too. Reverse the polarity on them and you can use them as a crappy microphone.
- coldtea 9y agoIt's also the other way around. Leafs when shaken produce waves in return.
- Matumio 9y agoYou observe leaves shaking when there is wind (a correlation). To test for causality you need to make an intervention. You still the leaves - the wind keeps going. You block the wind - the leaves stop shaking. There clearly is an asymmetry here. The physical equations may be symmetric, but this doesn't justify calling a microphone "speaker".
- coldtea 9y ago>The physical equations may be symmetric, but this doesn't justify calling a microphone "speaker". Actually a speaker is just a microphone with very small adaptations depending on the use (polarity, noise sensitivity, etc). But this is not about the wind, but about sound. The wind you describe is external ("You still the leaves - the wind keeps going"). But you can just as well have a wind produced by the leafs themselves.
- nkoren 9y agoThe sound is re-constructed from the shaking of the leaves. It's quite analogous to the way the sound is initially constructed from the vibration of a speaker membrane. The difference being that the medium of vibration which is used to propagate the "sound" is digital video rather than air.
- Someone 9y agoOne could say these objects are both. They pick up sound, acting as microphones, and send it back out by vibrating, acting as speakers (amplifying it by a factor of less than one). The camera acts as the microphone for ‘hearing’ that sound. I think you could hear that produced sound with a traditional microphone, but you would probably call it the echo of the original sound, and it might be hard to hear it over the original, typically much louder, sound.
- mattnewport 9y agoIt would be much more accurate to say these objects are neither speakers nor microphones. It is not a surprise that all objects vibrate in response to sound waves. What characterizes speakers or microphones is that they are transducers converting between acoustic signals and electrical signals. None of these objects are transducers so it's not accurate to call them speakers or microphones. It is reasonable to refer to the system of camera plus software plus observed object a kind of microphone but certainly not to refer to the observed objects as speakers or microphones. An aeroplane flies through the air and a submarine travels through the ocean. I can throw a rock into the air or into the ocean, that doesn't make a rock an aeroplane or a submarine.