Try searching for “sound absorbing window vents” or “accoustic trickle vents” or “silent air vent”.

I think they all use something that is called an air maze. The air (and sound) will travel through series of bends covered with foam so the sound will be blocked but not the air. This does make the airflow slow down so it needs a fan the make it go through.

If that is the case, there are also fresh air thingies that are mounted on the wall and have a tube outside but block any sound from outside. Useful when having a bedroom next to a busy road.