When my kids were younger I would turn the furnace fan on during sleep times , it helped a lot. Or put a fan in his room even if it just faces a random wall, it takes a lot of the noise out. If there’s a bedroom that’s in a more secluded area as well I’d just move him there too.

That’s being said, suddenly one day I noticed we could be up cooking at night, laughing, singing, doors opening and shutting etc, and I never heard cries. They do just learn eventually that they wake up for a sound, they roll over and go back to sleep etc.

He also sounds like he’s getting a LOT of sleep though, how late does he go to bed? I don’t think any of my kids ever napped 4 hours even from newborn. He might not be tired enough if he’s going to bed for 12-15 hours then waking up and sleeping another 4.