Eli5: how does a microphone work?
In: Engineering
Sound vibrates through the air. Those vibrations eventually hit what’s called the diaphragm on the microphone- the diaphragm then vibrates just like the sound wave. The diaphragm is also connected to a little coil, that coil sees those vibrations and turns them into an electrical signal. When you add a lot of volume (aka gain) to that electrical signal, you have an audible sound.
Fun fact, microphones and speakers effectively function the same, but backwards. If you wire things correctly, you can yell into a speaker and use it like a microphone.
There are many different types, Dynamic and Condenser are the most common ones.
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In a dynamic microfone a membrane is linked to a magnet, and circled around that is a ring of cables, called coil. This principle is called “Induction”.
When we speak we move the air around us and if that air hits the membrane, it starts to move, and with it, the magnet.
Because the magnet is inside the coil, it translates the movement into electric waves which we can now use.
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In a Condensener there’s no membrane, just 2 tiny little gold metal plates really close to each other. Connected to these is the condenser.
When we apply power to this condenser, it starts to look at the golden plates. When we now speak into the mic, one of these plates starts to move and this is registered and translated from the condenser into electrical waves.
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Now here comes the clue.
In order to hear it again, we need to do the same thing from the beginning but in reverse, because a dynamic microfone in reverse is called a speaker.
A Membrane is linked to a magnet, and when we insert an electrical wave into that coil, it starts to push and pull the magnet which moves the membrane and makes the sounds again.
TLDR: Every Sound is just an analog waves which moves the Air around us. Microfones use different methods like Induction or Capacity to translate these analog waves into electrical waves.
Don’t quote me as i’m going based off what I roughly remember from my engineering class.
So, sound is just vibrations in the air. The air wiggles, how much it wiggles is the frequency (Lower tones wiggle the air slow, higher tones wiggle the air very fast)
Microphones have a tiny sheet, kinda like your eardrum, it vibrates once the soundwaves reach it. This sheet is attached to a magnet, it vibrates too. Around the magnet is a coil of super thin wire, and when you move a magnet through a coil of wire it creates a little electric current. This little bit of electric current is then amplified, it makes that electric signal much ‘louder’ in the sense of it used to be a tiny current, but now it’s a big current that can be pushed over to a speaker or mixing board or whatever recording device and understood.
Funnily enough, speakers are essentially just a reverse microphone. The current from the microphone in turn uses a coil in the speaker to vibrate a magnet attached to a diaphragm. *(But this diaphragm tends to be bigger, like if you’ve ever seen a subwoofer playing bass tones, it vibrates like crazy)*
A couple fun science youtubers (I believe ElectroBOOM has done it) has messed with this concept, and has turned a microphone into a speaker itself, and made ‘speakers’ out of random items by just vibrating them.
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