How can sound be recorded into physical and digital media, what sorcery is this?

cheese_greater@lemmy.world to Ask Lemmy@lemmy.world – 51 points –

Also: can mp3s be totally represented as a text file?

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While it sounds simple enough to say 'waves captured in media reproduce sounds' it's still pretty mind bending to note that we can capture all the distinct parts of a symphony in that one wiggly little groove of a record.

That is because of linearity/superposition - look up both of those concepts for more info. Basically, you can add as many sounds together as you'd like and it is the same as a single, different sound - so if you can recreate the one sound, you can recreate all of them.

The speaker doesn't know "this part of the wave is from the drum and that part is from the guitar", etc

Which is still mind blowing in its own right. What's incredible in the end is not so much the process of sound recording as the nature of reality itself.

For this part of the equation I find it useful to think of two tin cans with a string between them, which is a perfectly capable microphone/loudspeaker set-up.

Which in turn makes sound isolation even more mind-blowing!

"this part of the wave is from the drum and that part is from the guitar"

So is that information deduced by the listener's mind, as opposed to their ear? Kind of like depth perception in the field of vision?

In short, yes.

Ear as an organ is not a simple microphone though. It’s partially evolved in a way to help humans recognize ‘the music’ and ‘the speech’. The brain does the heavy lifting.

It may help to remember that you only have two ears to hear that entire orchestra. So with only two speakers, you can reproduce said orchestra. By the time it makes it to your ear, the sound vibrations aren’t a bunch of separate waves; They have combined into a compound wave, with all of the constructive and destructive interference that goes along with that. What you hear is the sum of all the sound waves around you, not each individual source of the waves.

The Fourier transform is a way to convert from a raw waveform into all of its distinct parts, and back again. Computers do this for some types of sound data compression, such as MP3. Your ears do this (in the cochlea) when converting the physical movement of sound waves into electrical signals for your brain.