After a BI people lose their auditory filters. I remember all the sound came in at the same time. I could also hear sounds that no one else could hear. I picked up everything and echos were a major issue.
Recently I've been acoustically treating a room to get rid of echos and medium to high frequency sounds with high density acoustic foam panels. (Homemade based on YouTube videos)
The reduction in echos and high pitch sounds is amazing.
Although I don't have an issue with filtering these sounds anymore I thought WOW these would have been handy when I did have an issue.
I thought I'd just share this for people experiencing auditory filtering problems. By having them in your room you won't need to wear specialist frequency reduction earphones anymore in that space. (the panels may even be cheaper than acoustic reduction earphones if you can source the materials and make the panels yourself).