earplug were suggested.
what about earphones, the in-ear kind and an amplifier, say a recorder. Set the volume you are used to.

There is another problem and it shows how adaptable the human mind is. We habituate. The brain compensates for the current acoustics.

eg when loudspeakers are placed in the roof of a marquee with delay to compensate for the speed of sound it lowers the necessary volume at on end and enhances the clarity at the far end. However the sound engineer is habituated to loud with high frequencies absorbed by the room and the bodies in it. So he is used to a hi-end roll off and is compensating. When it doesn't roll off he thinks the sound is tinny because his brain is habituated. And I am talking of a BBC engineer with very strong (if misguided) opinions. Not unknown in this parish.

So "get used to it" is not that far off the truth. Give it time and if the ears are not damaged by long hours at high volume then the brain will "uncomensate" eventually.