Problem: MacBook (or podium Mac Mini) connected via HDMI or USB-C video cable, have video but no audio.
Solution: Set audio output device in System Preferences.
-
On your Mac, choose Apple menu 
> System Settings, then click Sound 
in the sidebar. (You may need to scroll down.)
-
Click Output on the right, then select the device you want to use.
In classrooms, the Name label is either "Crestron" or "Classroom System" or "Room Speakers" in the list of sound output devices. The Type of device will typically be HDMI, DisplayPort, or USB.
-
You should only have to do this once in a new classroom setting. It remembers the setting and will recall the sound settings the next time you connect the cable to the same system.
Problem: Audio crackles or drops out when connected to HDMI cable in classroom
Solution 1: Reboot MacBook (too many open apps/windows have caused this issue).
Solution 2: On 2022+ MacBooks in rooms with HDMI cables with tethered USB-C adapters: bypass the USB-C to HDMI adapter and plug the HDMI cable directly into the MacBook’s HDMI port on the right side. Verify audio settings in System Preferences → Sound.