It seems I'm not good at keeping my promise and stay on topic. And now I have @Uncle Gizmo’s permission to go more off topic.They take a bit of getting used to, unless you're the type of person who, even with perfect hearing, the windows open and no radio on, couldn't hear your own car backfiring.
We had several car accidents here, and it came out that a walking person, couldn't hear a car approaching (an electric car) from rear and avoid the accident.
So new models of electric cars here make unwanted noise. Not from the engine. But they have a speaker to create engine noise as an alarm for others in narrow streets.
Being silent and noiseless seems not to be perfect.