Anechoic chambers are anechoeic, not soundproof. I used to have access to one, which was very quiet, but that was a side-effect. If you had a neighbor playing l

Anechoic chambers are anechoeic, not soundproof. I used to have access to one, which was very quiet, but that was a side-effect. If you had a neighbor playing loud music, e.g., it would still penetrate. There are some consumer acoustic isolation techniques, like sound insulation and brackets that isolate the drywall from the studs. I don't know how well they work.