eli5 – How does an audio signal accurately reproduce complex sounds?

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Tried to search, didn’t really find what I was looking for.

Whether vinyl, cassette, mp3 etc – how am I able to discern multiple different instruments in music perfectly clear from a single audio signal? How does a single groove in an LP allow me to hear a baseline and full drum kit and vocals clearly? I can understand one at a time but?

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4 Answers

Anonymous 0 Comments

Waves add together.

Even with a single instrument playing a single note, there are multiple frequencies, harmonics, and overtones that you’re hearing. These add together, canceling each other out in some places and strengthening each other in other places. This creates a complex waveform that can still be drawn as a single line on an oscilloscope – just not a simple sine wave.

No matter how many different sounds you add together, at any given moment in time, everything that’s going on adds up to a single value. That means that no matter how many instruments you’re listening to, the needle on the record only needs to follow one complex path to reproduce the moment-to-moment sum of everything the mic picked up. A digital audio source is doing the same thing, just capturing a single number thousands of times per second.

The magic happens in your ears and brain where your cochlea unscrambles all the different frequencies and your auditory cortex interprets them into meaningfully distinct sounds.

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