This is a massive exaggeration. I'm aware this is anecdotal but I work close to the centre of a large city with 18000/sqm density (according to wikipedia) and I

This is a massive exaggeration. I'm aware this is anecdotal but I work close to the centre of a large city with 18000/sqm density (according to wikipedia) and I honestly can't recall the last time I heard a siren or car horn.