Eli5 How do headphones make voices and sounds so accurately?
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ALL SOUNDS are just pressure waves in the air. With a microphone, you are just recording very precise and accurate changes in air pressure.
Headphones (and any other speakers) just move little diaphragms with a similar precision, replicating those changes in air pressure.
A few things to get out of the way:
* Sound is what our brain interprets from pressure waves in the air hitting our eardrums, which is a thin membrane. The exact mechanics aren’t important here, but the “thin membrane” that moves due to pressure waves is the key thing here.
* The flow of electricity can be modeled as a waveform pretty easily.
* When a magnetic field and a significant length of conductive material move in relation to each other, this creates a magnetic charge with properties that are similar to the movement of the entities.
* When an electrical current goes through a coil of wire, a magnetic field is generated, and the polarity (that is, north/south) oscillates mimicking properties of the electrical waveform of the current.
So: when we record voices, we are using our mouth to make pressure waves towards a microphone. A very basic bare-bones microphone consists of a body, a thin membrane, a coil of wire, and a static magnet. The coil of wire is attached to the membrane, and the static magnet the body (this could theoretically work the other way around, and might in some microphones, but the ones I’ve taken apart have all had them in this configuration, more or less). Our talking moves the membrane at around the same frequency as our voices, and this gets translated by the microphone into an electrical signal that can then be recorded through various means to recreate that exact same electromagnetic signal again.
The headphones/speakers, then, are the inverse of the microphone – instead of sending electricity in to be recorded, they conduct the recorded electrical signal back out and the inverse process moves air that then pushes into your ear.
Now, there is more than that to making them *accurate* – you have some issues to work around with regards to volume of input signal vs maximum amplitude of the waveform a given microphone can handle, and this can cause distortion to occur. There are other things, like how microphones don’t handle hard “p” sounds (like in “popcorn”) very well, and different techniques such as pop filters were developed to smooth over the capture and not make the pop in the P blow your ears up every time it happens on the recording.
It’s mostly been people analyzing sound waves and electrical waves to catch the differences and studying how humans interact with sound that has made things incrementally get better in quality.
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