I’m autistic with relatively high sound sensitivity. I’m wondering if another autistic person in this community used any soundproofing in an apartment that actually reduced noise coming from a busy street. There are a lot of different products out there and I don’t want to buy something that doesn’t work.
Replace your windows with thicker glazing. Or if you live in a rental you can add sound proof secondary glazing in front of your windows. And for the rest of the room the best way is to build a room inside the room with soundproofing insulation behind the walls. Or hang Mass Loaded Vinyl against the walls.
Basically proper sound proofing is expensive as fuck. Cheapest is a good pair of active noise canceling headphones and custom fit earplugs.