The Lenovo Yoga's have HDMI, and by default HDMI has the ability to push audio. The problem is that most podiums on campus do not use HDMI for audio and you must use the headphone jack.
When you plugin your laptop to HDMI, it will try to send the audio out this line by default. You'll need to manually tell the system to send the audio out through the audio jack. Here's how to do that.
First, connect both the HDMI cable and audio cable.
Once connected, left click on your speaker icon in the system tray near the time.
Click the ^ in the upper right to expand the menu.
Select Speakers / Headphones and the audio will now go out the audio jack.