Synthesizes music is free of ambient noise or distortion captured by a microphone. As such, its fidelity can be much higher than naturally recorded music, increasing demands to reproduce it more accurately.
Years ago, when making computers make "music":
I learned how to tickle the sound chip in my Commodore 64 successfully, for three voices.
Then I got a Mac, and couldn't figure out how to coerce its sound chip to make tunes.
So, using Think C, I located the file format for WAV files and synthesized tunes sample by sample, finally getting to the point where I had 12 voices in stereo with reverberation and probably some other effects, writing the WAV file just a little faster than playback speed, so no waiting fore results (other than code tweaking).
Then got a Windows 98, unable to figure out how to tickle its sound device, and continued with C.
Then quit. It was a fun experiment, learned a lot about digital sound.
There was, of course, no noise or distortions unless I added it.
Here's a couple I can still find:
They sound repetitive, but really aren't, as a counter goes from 0 to 63, increments the second counter (which also goes from 0 to 63), and the two numbers are OR'ed or XOR'ed or AND'ed or whatever else I could think of at the time to get the pitches from a 64 note pitch table for each of, sounds like, three voices here.
So, every "64 note bar" is different, for 4096 bars.
www.dropbox.com
And another, same concept, different note picking algorithm from the counters:
www.dropbox.com