As the various conference rooms on campus (and the Science Lecture Hall) have been modernized over the past few years most of the projector and speaker connections in these locations have been switched over to HDMI. This means when you plug in the HDMI cable into your MacBook you may not hear any audio coming out of the room’s speakers.
To change your audio output to HDMI follow these steps:
1. Go to the Apple menu in the top left hand corner and then select System Settings:
2. In this window, from the list on the left hand side select Sound and then select the device that has HDMI listed in the Type column:
Any audio playing should now come out of the room’s speakers. When you unplug the HDMI cable the setting will reset so that audio will play out of the laptop’s speakers.