system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why did the dial-up sound have to be played out loud?

Hi guys - I'm wondering why the dial up sound was even something we can all remember? I'm sure there are plenty of processes occurring with our wireless networks that could make crazy sounds but the computers specifically don't play them out to us.

Was the dial-up sound mechanical in nature and had to played out loud? like a mechanical hard drive spooling up?

I hope you understand, I found it hard to put down in words.

Thanks!
gpt
It contained diagnostic information- i.e. you'd hear things like "all circuits are busy" or if it was the wrong number, etc.  There are also loads of retraining signals that can give an idea of how fast you are connecting, as well as noise on the line, etc.  

Then after awhile (early 2000s) the cheapest software "winmodems" didn't have a speaker, and would instead play a .wav file of a 56K modem connecting successfully, which was pretty evil, IMHO.