Simply isolate the washing machine completely from the building. Levitate it entirely off the ground, suspended in the air via a massive toroidal superconducting electromagnet, 3 meters in diameter, cooled by liquid helium. (Which will need to be regularly topped off. It tends to slowly leak through solid walls.)
The noise would be greatly reduced. As the machine thrashes about, it will do little but disturb the air around it. Little noise will be generated, except from the sound of the machine’s own parts acting against each other.
Though, if you really wanted to optimize this for this setup, a different design is in order? Perhaps a non-standard design would better handle internal vibrational damping? Have you considered calling local stores and asking if they have any spherical washing machines in stock?
I propose the most practical option possible:
Simply isolate the washing machine completely from the building. Levitate it entirely off the ground, suspended in the air via a massive toroidal superconducting electromagnet, 3 meters in diameter, cooled by liquid helium. (Which will need to be regularly topped off. It tends to slowly leak through solid walls.)
The noise would be greatly reduced. As the machine thrashes about, it will do little but disturb the air around it. Little noise will be generated, except from the sound of the machine’s own parts acting against each other.
Though, if you really wanted to optimize this for this setup, a different design is in order? Perhaps a non-standard design would better handle internal vibrational damping? Have you considered calling local stores and asking if they have any spherical washing machines in stock?