Forced ventilation from a window to cut out the noise
So I live on a busy street with lots of polluting cars and buses. Wouldn't it be grand to build a duct work system from the window into the room with a few turns, perhaps a muffler of some sort to block the noise, then a quiet fan with a Hepa filter at the end to filter city air pollution. I have yet to see anything like this done online. Yet billions of people live in noisy areas and their sleep, work and general quality of life suffers because of it. Is it that difficult? I'm just looking at positive air pressure. There are lots of gaps and crevices where the air can go once pushed into the room. I haven't seen any ventilation fans that are quiet so I was going to use 4 x 120mm fans (about 4" square each) instead as these can be run so they are almost inaudible at a few feet away. I think the main challenge is going to be to filter out the midrange sounds from outside.
Yes, that would solve some problems. But I realized that even if I'm away from traffic and people, nature still makes quite a racket sometimes. Crows and other birds are pretty vocal, especially in the morning, and I often am up late at night so I need to sleep in.
In a natural setting the way to accomplish this would be to sleep at the end of a long cave! That's your ductwork. The twists and turns and irregular walls would stop a lot of sound from getting to the back. Now about those bats......
Seriously folks, imagine someone's in an adjoining room making a lot of midrange noise coming through the ductwork. What are some ways of reducing that noise?