At a guess, your system is probably reverting back to the default audio device on resume.
What does it look like in Settings after resuming? Can you change the audio playback device back to HDMI by hand? ** Changed in: pulseaudio (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to pulseaudio in Ubuntu. https://bugs.launchpad.net/bugs/1718927 Title: No hdmi sound after suspend/resume on 16.04 Status in pulseaudio package in Ubuntu: Incomplete Bug description: When plugging in a HDMI TV to Lenovo Carbon 3rd Edition, sound works perfectly, but when I suspend computer and resume it there is no sound via HDMI in TV. However sound via built in speakers works fine. The only thing I can do to restore sound is to reboot the machine. Similar problem was discussed in following thread https://ubuntuforums.org/showthread.php?t=2251651 with no solution. I tested it on several versions of kernel 4.4.0 and on 4.4.8. Still no solution. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1718927/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp