>>>>>Yeah, right. Maybe if you live in the Okefenokee Swamp.
No, but if you live in say Arizona, or you don't humidify you house in a cool climate, then yes humidity can dip into the 10-30% range where frequencies can be attenuate in a large room, especially if you have a "lively" room total energy at higher frequencies is more dependent on bounces extending path length. 10db would be more a concert hall / outdoor venue figure, but completely possible.