[dealuromanet]

You'd need police officers in police cruisers waiting for the sign of trouble. The officers would communicate with one another when they notice a loud vehicle pass by. Then they can use a noise gun to get a decibel reading. This is an intentional physical bottleneck placed on the surveillance apparatus so that it is limited to only identifying and pursuing those cars that are too loud. You would have the same end result if the fines are hefty enough without needing to build and deploy a surveillance dragnet that you won't be able to escape from once it exists.

A town or city would do better with a few police officers in cruisers keeping an eye on things than with these boxes deployed on every streetlight listening 24/7.