This is the loudest city I have ever been in.
As I speak, there is a symphony of horns outside the open door of this internet cafe. Drivers use their horn for anything and everything. They honk if someone is going to slow, if traffic is stopped in front of them (for, say, a red light) if there is a pedestrian walking by the side of the road or cowering in the median waiting to cross, if there is a car waiting at the red light they are going through. It's particularly important to honk if you are going the wrong way down a major boulevard, making a turn (legal or illegal), or squeezing between two lanes of traffic.
Conversational Yemeni Arabic is louder than conversational Cantonese -- and that's saying a lot. And people yell at each other for the slightest reason.
I'm a high school teacher. Passing time in a high school, the few minutes when 1200 teenagers are on the move, is loud and chaotic. It can be traumatic for visitors who aren't used to it. Being in Sana'a is like being in passing time 24 hours a day. I don't know how people stand it.