Hanoi can't exist without people yelling at you prices of their menus, their silks, their lovely coffees, the sound of scrap dealers working the metal on the street or any horns symphony. That wouldn't be Hanoi ! So pay attention while you walking through Hanoi, if you don't want to finish your life lying down the road. Horn are the only way to say get out my way..there is no others rules. This is a busy city if you are concentrate on the noise, you'll probably find it really stressfull, but if you look at people you'll only see serene faces. It is like time doesn't matter. Now focus on that point.