eli5: How do speakers know which part of the song to play?



When I listen to a song on my sound system, one speaker will have the guitar whilst the other will have the vocals. How does the sound system distinguish it within the song?

In: Technology

Someone had to go in and add that information to the recording. Basically, there is data in there that says “ok, play this on the back speaker on the left and play this other bit on the front speaker on the right” And an audio engineer had to set up the recording to do that properly.

Now your question might be “how does a speaker know where it is”

Simple, they don’t. When you hook up a sound system you almost always have to manually hook the speakers up correctly. Basically, you have the plugin the speaker you put in the front on the left into an outlet that’s going to be labeled “this is where you plug in the speaker you are going to put in the front on left”

The speakers only play what they are told. See, most audio is saved in distinct channels – vocal, guitar, drum, etc. – and most playback devices have built-in filters to point each channel to a specific speaker. Some times, this is even more finely tuned, so that something is channeled to more than one speaker at once, so you can hear it in stereo. And some things are so old, there’s only one audio channel in the track.

Your speakers have to connect to something, usually an amplifier or receiver – this is usually a box.

This box has a chip inside it. When music goes to this box, this chip will try and figure out how to send different parts of the song to the different speakers.

Sometimes movies or TV shows are made with 6-8 different sound tracks – each is for a different speaker. The box gets all of these, and then sends the sound to each speaker.

Most audio has 2 tracks. Then the box will try and split these two to various speakers.