Acoustic Treatment

Treatment means putting soft, dense material where reflections hit: panels at the first reflection points either side of you, something on the wall behind the microphone, a rug on a hard floor, and bass traps in the corners if the room is small. What you are killing is the short slapback that makes a voice sound like a voice recorded in a box. Soundproofing is a different job entirely and needs mass and air gaps built into the structure, which is why foam on a wall does nothing about the neighbour's dog. For most creators a duvet, a bookcase and a closer microphone get most of the way there.