A Question about a magic item in Of Sound Mind

[JoeBlank]

PC, I just finished OSM, and one of my players is using this magic item now. I made one change though, I have it give a plus to listen checks. I believe as written it gives a minus, but my players never would have used it if that was the case. Maybe I will spring a minus on the player when conversation is overheard while trying to concentrate on hearing something.