In my case, HDMI audio was glitchy (using the latest 201 Debian release). The solution was:
 Reinstall PulseAudio
sudo apt-get -y remove --purge pulseaudio
sudo apt-get -y install pulseaudio
sudo apt-get -y install pavucontrol
 Edit file “/etc/pulse/default.pa” and include “tsched=0” (after load-module module-udev-detect):
load-module module-udev-detect tsched=0
(look for “Glitches, skips or crackling” in this reference)
Note: maybe, step  can be skipped (I just tried it first). Steps  and  may fix the issue.
I hope this helps.