Question about how analog audio recording works
Hello!
My wife and I are high and having a discussion about how sound is recorded on records. I have an, I think, more than average understand of how sound and recording/playback works so I was trying to explain how grooves on the record represent sound waves.
What we don't understand is how polyphony is physically represented. So I can see how a single sine can easily be represented on a record. But when you're talking several sounds at once, some on the same pitch some now, dozens of timbres happening all at once, how do we differentiate those sounds on a physical medium like vinyl, or how do we represent it digitally? Is it literally nothing more than 1s and 0s? That'd be sick
Anyway, I hope this makes sense. Thanks!
In air, there's no such thing as polyphony. Air pressure is either rising or lowering. The sound of a violin, or drum, or any complex sounding instrument at any instant in time is creating pressure at a microphone which is either going up or going down or still when silent. That up and down is what a vinyl record tracks, and what a speaker driver represents as it moves towards you or away from you. |
@dweller Full range drivers are not an example. They fall all over themselves all the time due to breakups and something called the Doppler Effect. Finally, 'full range' drivers don't exist. All of them will need a subwoofer and a tweeter (to fix beamy-ness); in essence 'wide range midrange driver' is a far more accurate description.
|
Compact discs do not have 1's and 0's embedded in the polycarbonate. CDs have a series of pits on an aluminum layer arrayed in a spiral pattern. A red laser follows the spiral groove from the center outward. The reflected laser light is read by a photo detector which converts the light into varying voltages according to intensity. The data on the CD is encoded by the different distances between the pits. These distances are called "lands". A transition between a pit and a land can be either a 0 or a 1. It is the transition between pits and lands that is the basis of optical data encoding. |
