Compression Ranges in Adobe

I am trying to post an audio book to Audible and they are asking for the already recorded files in a range of -18 to -23db. Seeing as the files are already recorded I need to go back in and edit them down. I am asking if there is a way of setting a compression range and then applying that range to the already existing files.

Doing this manually sucks. There are quite a few files that need to edited down.

Thanks

Mitch