A speaker running backwards
How Does Your Voice Get Recorded?
A microphone lets air pressure flex a thin sheet, then turns that movement into numbers.
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Step 1 of 5
Your voice arrives as changing pressure.
Speaking sends ripples of slightly squashed and slightly stretched air outwards, and those ripples are the only thing that reaches the microphone.
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Step 2 of 5
A thin sheet copies the pressure exactly.
Inside is a membrane thinner than paper, light enough to be pushed by air alone, so it traces every wobble your voice makes.
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Step 3 of 5
Moving the sheet changes something electrical.
In one design the sheet drags a coil past a magnet; in another it forms one side of a charged gap whose width keeps changing.
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Step 4 of 5
The result is a wobble matching your voice.
Loud sounds flex the sheet a long way and make a big signal; quiet ones barely move it. Silence leaves the sheet sitting perfectly still.
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Step 5 of 5
It is stored as numbers, thousands a second.
The wobble is measured over and over and each reading is written down as a number, so the sound becomes a very long list of measurements.
CD audio measures the wobble 44,100 times a second, because capturing a sound faithfully needs more than twice its highest frequency.
The short version
A microphone records you by letting air pressure flex a thin sheet, turning that movement into an electrical wobble, then into numbers.
Try it yourself
Hum steadily into a phone voice recorder while cupping and uncupping your hand around it. The trace on screen changes shape as you do.
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