Noise cameras. Just like a speed camera, but it measures noise levels and issues a ticket in the mail. There's unfortunately a regressive element (some people can't afford to fix their noisy exhaust), but I see no reason not to issue tickets for noise outside of normal hours, e.g. 7am-10pm.
I'd guess that most people working "outside of normal hours" are doing it by necessity doing some kind of low wage job, and therefore poorer. e.g. anyone who works in restaurants or bars or music or nightlife after 10pm, taxi drivers, pizza delivery, Uber drivers, 24/7 gas station and supermarket employees, security guards, delivery truck drivers, garbage collectors, train drivers, etc.
Noise cameras. Just like a speed camera, but it measures noise levels and issues a ticket in the mail. There's unfortunately a regressive element (some people can't afford to fix their noisy exhaust), but I see no reason not to issue tickets for noise outside of normal hours, e.g. 7am-10pm.