To clarify, I understand magnets vibrating fabric, and how that produces noise. I do not know how one constantly vibrating thing can produce multiple tones at the same time as required for music. Like base and trebels together in songs, how can you hear both at the same time?
In:
It sounds like you understand the mechanics of how a speaker works. It simply vibrates in a way that creates a complex wave of energy in the air. If you zoom in on a sound wave in an audio editing program you’ll see a complex shape made up of the additive and subtractive peaks and valleys of multiple frequencies. The speaker creates a wave of energy in the air that looks like that. The magic happens in our ear. That complex wave of air compression and rarefaction is decoded by our brain into the constituent frequencies of that complex wave. Since nothing that I know of in nature produces a perfect sine wave this phenomenon occurs with every sound producing thing… not just speakers.
I can totally see how this is confusing, it might help to think about a speaker as a reverse ear – they both have surfaces that move with the changing air pressure. Your ear has no problem hearing two different tones at once.
The reason this works is the idea of superposition – when you have two tones playing together they add up to make a complicated shape. These tones can be split up by clever maths (fourier transform) or by your clever brain.
I guess it’s a bit like a pixel on the screen you’re looking at right now. There are three ‘tones’ red, blue and green. When you have multiple of these ‘tones’ on in the same pixel they mix together to make another colour, but still contain all the information from the base colours, which can be separated from each other.
When you see a waveform in a program like Audacity you’re seeing the result of adding all these tones together. The speaker follows the waveform shown, but it is built from lots of different tones which can still be extracted.
If you do an image search for superposition you’ll get a better understanding of how all these different frequency components add together.
Your ear also works basically by an eardrum, a single surface that vibrates.
Tones are simply a question of vibrating frequency. Bass is very slow vibration, high-end sounds are very rapid vibrations.
If you scratch a chalkboard, your nail doesn’t really carve the board, it jumps/taps super rapidly along it making sound at each contact. So it interacts at high frequency and produces treble.
If you hit a bass drum, it vibrates rather slowly, creating bass.
But you can, mathematically, add one wave to another, creating a mixed wave of both. If they’re different enough by themselves, your ear can distinguish between both. That’s a typical concern of electronic music producers, to make sure bassline doesn’t drown out the kick drums and vocals don’t get muddled with mid-frequency synths where you cannot clearly hear neither. Well-produced track avoids those problems.
If you add same shape of wave together, but other one’s inversed, you get silence. 1+(-1)=0. That’s what noise-cancelling headphones, putting it bluntly – try to do.
So ELI5 answer is that waves are just bits of math that can be added and subtracted and mixed. In the end, it’s just vibration with different bits at different frequency happening in rhythm.
Imagine you’re jumping up and down in rhythmic fashion – this is like the speaker vibrating to play a single frequency. Your movement roughly looks like [this](https://i.imgur.com/2aF23fj.png). (Since this is ELI5, ignore gravity and acceleration and all that stuff, just think of simple back and forth movement).
Then, imagine you’re doing this in an elevator going up and down. Say you’re jumping up and down quickly while the elevator is going up and down slowly. Your movement looks something like [this](https://i.imgur.com/Gfmxwbu.png).
Your movement relative to the building (which is stationary) is like the vibration of a speaker playing two tones at the same time. One note is the higher pitched sound represented by your jumping up and down, the other note is the lower pitched sound represented by the elevator: two tones in one without any problems.
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