This reminds me of the drama the architect & acoustic engineers went through, when building the Sydney Opera House. They realised that if the toilets were used during a performance. The noise of the conventional dunny  cisterns, would be amplified & create problems. Caused by the unique structure of the building & the number of loo?s through out it.
This was obviously resolved, but at great cost to the state government, putting silencers on  the bog standard ?Sir Thomas Crapper? water valve toilets.
 Attempting to modify the ?thunder from down under?!