Originally Posted by filburt1

Unless you talk at 90 dB, you're not disturbing the peace.

I really don't see how there can even be a debate about this. The music was loud enough to disturb others, which also means it was too loud to allow you to drive safely (I don't care how well you can see...driving requires tactile, visual, and auditory feedback). He was right to get the ticket, and hopefully will learn to keep the volume down.

It's also why cell phones are illegal in many places now where driving, including DC. It's a distraction: your brain is focusing on the conversation (or the loud music that can't be ignored) so you aren't devoting your full attention to the road.