system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is is when I'm put on hold with customer support, the music sounds like it's being played through a damaged speaker?

The conversation with the person on the other side will be clear as day, but the music when I'm on hold sounds horrible.
gpt
I would assume for the same reason that voices sound like damaged speakers as well: they cut the frequency range down to reduce the amount of energy required to transmit the signal.
It's something like 340-3000 or 3500Hz (which includes the very important mid-range frequencies for human speech) instead of the "full" range of 20-20000Hz for humans.
There's basically no bass, making it sound very lo-fi.

edit: furthermore, the songs are compressed and in mono, making them victims of phase issues, creating slight "disturbances" that can make a song sound a bit washy. Most professional mixes keep these to a minimum but it's impossible to eliminate them.