Hi, I had an issue a few weeks ago very similar where I could not hear people or even see their typed messages. Instead of audio, it could very much be suddenly related to your Xbox/microsoft account settings. If you log in to your microsoft account, go down to your privacy settings and you should see a section titled "You can communicate outside of Xbox with voice & text" make sure it is turned on to "Allow". I have never messed with this setting, but for some reason it was turned off and muted all my in game chat functions.
If it is truly audio related I'm afraid I don't know what to do... microsoft has never played well with SOT audio functions :(