There was some research done on psychedelic hallucinations which revealed that there is actually less sensory input and that so filters are not disabled - they just have less work as there is less input.

With less input the brain hallucinates to fill in the gaps. It may feel like the doors are being opened to allow the outside in but hallucinogens close the outside off. Your heightened perception of external things when on psychedelics are hallucinations occurring in your brain and not some objective information being transmitted from outside