I have an extremely frustrating problem with Ubuntu 16.04 LTS 64-bits on my Dell E7450: when I connect a TV over HDMI (tried a Samsung 1080p TV via this 25-ft high-speed HDMI cable with Ethernet support, and also a Visio TV via a 6-ft cable), MOST OFTEN BUT NOT ALWAYS the sound is 2x as slow, and everything else, e.g. video playback, is dragged down to slow-motion.
In other words, testing audio via Speaker Testing goes "Frooont Leeeft" in a low-pitch male voice (the normal is a crisp "Front Left" in a female voice").
After some frustratingly random combination of reconnecting the cable, switching among display mirroring modes and rebooting, the sound returns to normal - as long as the laptop doesn't enter standby mode.
This drives me nuts. Any solutions?
A bug for this behavior was reported in May 2016:
https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1580882
The workaround suggested in the 2017-Jan comment worked for me as of July 2017:
(Since I got no answers on this question, I had initially reported the bug at https://bugs.launchpad.net/ubuntu/+source/unity-control-center/+bug/1620192; it was marked duplicate.)
To complement the above, if you read through the comments on the bug, you'll see that there is a fix/workaround which consists in the manual installation of an updated package from here (further instructions).
Basically for a 16.04 desktop, I chose the "daily" build of package
oem-audio-hda-daily-lts-xenial-dkms
at the bottom of the page, then:oem-audio-hda-daily-lts-xenial-dkms_0.<timestamp>~ubuntu16.04.1_all.deb
(at bottom of page) which opens in the package managerI experienced this bug on my laptop (a ThinkPad X1c3) when it was still running trusty; when upgrading to Xenial didn't fix the issue, I thought it was time to do smth about it. Glad it's finally fixed!