I'd say the loudest place I have been to was downtown Johannesburg. But only the parts that are overcrowded with hijacked buildings and a million people on the street / trying to sell stuff to you. I'll try and get a video of the craziness when I am back in October of this year. The suburbs are incredibly quiet though, even on neighbourhood high streets.
It's hard to tell from street view but driving down here was an assault on the senses:
https://goo.gl/maps/eNEEH2Td7AH2