If you are using Bluetooth audio for Forza Horizon 5 and experiencing no sound, this guide may help
Players will need to Disable the hands free setting for your headphones in the audio devices management screen of your windows audio settings
- go to bluetooth settings.
- your bluetooth headset should show "connected music, voice".
- now, go to control panel -> sound.
- on the "playback" tab, your headset should be shown as a hands-free part, and a headphones part. Now, disable the hands-free part, and go to the "recording" tab and do the same.
This should allow your to hear audio in game now.