making MP3s the same volume - is there an easy way?

I love listening to audio-books from Unfortunately some of the collections of short stories are - erratic in terms of volume. This is annoying as I keep having to adjust the volume.

So is there any easy way to make these MP3s the same volume?

(yep I have used the word volume too many times)

MP3Gain gives it a shot. I’ve only played with it once, for a live bootleg album, and it worked fairly well. It does want to re-encode the files though, and I’m not sure it’s worth it, to be honest.

Not exactly a ringing endorsement, I know.

Mp3gain works great and does NOT reencode the files. If you do not like the results, any changes can be undone.
ETA: Make sure you get Mp3gain, not Mp3gain Pro. They are totally unrelated programs.

It definitely changed the files I tried it on. Does it just change the volume embed in the file then? In any case, it doesn’t work on the fly (or didn’t, it was a few years ago)

It changes the volume levels without re-encoding the audio stream itself - so it’s entirely reversible.

mp3gain reads the entire file to determine the “loudness” of the mp3 (based on a model of human hearing).It then modifies a field in the MP3 header that some players use to determine output gain, thus modifying the output level appropriately. Not all players honour the gain setting, however. mp3gain will also treat all the tracks in an album together, so that the relative volumes of all the tracks on an album are correct.
I run it across my collection. I used to set the volume so that a MP3 player could not set the output level to ear damaging levels even if turned up to max volume. My kids complained, but I was happy their ears were a bit safer.