Echoey walls and dust mites

I expect this question is beyond normal discussions here.  I’m looking for solutions to deal with an echoey listening room.  My problem is that I have a severe dust mite allergy and normal anti echo solutions won’t work.   

Floor is hard wood, walls smooth — not what you’d want for best listening environment.  Carpets, curtains and the like are breading grounds for dust mites.  Steam cleaning doesn’t work as the mites survive.

Are there hypoallergenic sound baffling thingies that might be wall/ceiling mounted that anyone is aware off.

BTW.  I had explored sound deadening paint and that’s not really a solutions (yes that does exist).

Ideas?

TIA for ideas.

— Eric