The first thing to check is if the audio issue is just in the online classroom or if the audio issue is happening across all your applications. To test it, try anything that usually would give audio such as play a video at YouTube. If you cannot hear anything there, then you know if is a setting on your own computer or perhaps your speakers or headphones have failed.
If you can hear in other applications, then you will need to adjust the settings for the classroom.
If you can hear in other applications, then you will need to adjust the settings for the classroom.
The BigBlueButton Knowledge Base has some resources for you to search to troubleshoot. Please click on the link below: