There are multiple ways to troubleshoot not hearing others in a Space. Here are a few ways to fix that. We always recommend first reloading the page as that fixes most issues.
Test Speakers in the Space:
When in a Space, click Setup > Device Setup > Test Speakers. If you can hear a tune playing then your speakers are working just fine.
Test Speakers in the Lobby:
When joining a Space, test your speakers in the Lobby. You can see how in this video:
Choose a different audio source:
Check the Device Setup menu and choose a different audio source.
Check your device or headphones:
Make sure that the hardware you're using is not on mute. Click the icon to unmute and turn the volume up on your hardware. If possible, use headphones for better audio quality.