An interesting article on @BBC_Future about how silence following on from loud noise appears more silent than silence heard after something quiet. I have been to many silent places (anechoic chamber, flotation tank, deserts) where there is no external sound and what you hear is internal sounds, noteably high pitched sounds which are probably spontaneous firings of the auditory nerve. Are these firings louder in silence following loud noise than silence following quiet? I don’t know, but they do change overtime (provided you don’t suffer from tinnitus) as the brain adapts to completely silent conditions. I remember hearing them disappearing. More evidence of the adaptation that @tomstafford writes about.