3 ms·
Right, it gets even worse: Air pressure in not only altitude-dependent but fluctuates even at constant altitude. The pressure (altitude) dependence is comparati
by _0ffh 2y ago
Right, it gets even worse: Air pressure in not only altitude-dependent but fluctuates even at constant altitude. The pressure (altitude) dependence is comparatively weak, though.
- KeplerBoy 2y agoone might say air pressure changes constantly as we speak.
- adammarples 2y agoIsn't air pressure the only thing that microphones actually measure?
- sojsurf 2y agoAir pressure differentials, to be precise!
- KeplerBoy 2y agoBy definition, sure. But one always needs some effect which changes some electrical property. We can't just hook up an ADC (analog digital converter) to thin air and hope for the best. In practice most microphones measure the displacement of microscopic membranes, which are deformed by the air pressure. The next question then becomes how to measure microscopic movements of a tiny membrane. Turns out the membrane forms part of a capacitor and the electrical characteristics of capacitors depend on their geometry.
- jpc0 2y agoThat is not necessary true. There are at least 4 different types of microphones. Condenser which does in fact form part of a capacitor, dynamic which is effectively a linear generator (coil attached to membrane), ribbon which is a change in resistance as a small ribbon flexes and piezoelectric which is some black magic witg crystals
- KeplerBoy 2y agoSure, that's why I wrote most microphones. There are also some exotic principles like laser or radar microphones using interferometry. https://en.m.wikipedia.org/wiki/Laser_microphone https://en.m.wikipedia.org/wiki/Laser_microphone https://ieeexplore.ieee.org/document/7808865 https://ieeexplore.ieee.org/document/7808865
- jpc0 2y agoI think popular is very situational though. For me I see a lot more dynamic than condensers but I guess if you are talking about what is in like every single IOT thingamabob then you might be right there.
- entropicdrifter 2y agoNo, you're right. Most microphones and speakers ever made are dynamic. The speakers do function as microphones, by the way. The difference is simply whether you amplify the electricity generated by the vibrations moving the membrane (microphone) or if you send a pre-amplified signal to the copper coil around the magnet (speaker). They work on the same principle, so any dynamic driver can work as a microphone and any dynamic microphone could work as a driver, all just depending on the rest of the electronics they're hooked up to.
- sanderjd 2y agoFascinating. Is there a book about the history of microphones? I find this to all be in the realm of "I don't believe you that any of this works at all" if I didn't have a lifetime of experience with the fruits of successfully-functioning microphones.
- immibis 2y agoMany types measure the derivative of air pressure. One that measures absolute air pressure can be used for calibration.