Suppose you're at a rock concert. You hear several string instruments, drums, maybe a keyboard, and a voice or two all together at the same time.
What reaches your ears is continuous differences in the air pressure. That's more-or-less a single changing 'amplitude'. From that, your brain can pull apart the fundamental and overtone pitches from each source ... and sort them out so you can identify each one. Amazing technology ... almost indistinguishable from magic!
These days lots of people haven't seen audio on an oscilloscope ... which shows changes in amplitude with time. Look at this video. You'll see that at each point in time (left to right), there's ONE amplitude, whether he plays one string or more.
What reaches your ears is continuous differences in the air pressure. That's more-or-less a single changing 'amplitude'. From that, your brain can pull apart the fundamental and overtone pitches from each source ... and sort them out so you can identify each one. Amazing technology ... almost indistinguishable from magic!
These days lots of people haven't seen audio on an oscilloscope ... which shows changes in amplitude with time. Look at this video. You'll see that at each point in time (left to right), there's ONE amplitude, whether he plays one string or more.
https://www.youtube.com/watch?v=Dd5dgajeIOA