Distorted sound from Focusrite after update

I have Ubuntu 20.04 and after an update today, my sound output became distorted (sort of metallic/robotic). I'm using an external Focusrite sound interface but my system has of course also built-in sound:

Audio: Device-1: Intel 200 Series PCH HD Audio driver: snd_hda_intel Device-2: NVIDIA TU102 High Definition Audio driver: snd_hda_intel Device-3: Focusrite-Novation type: USB driver: snd-usb-audio 

The distortion happens only on device 3. Other devices work correctly. I suspect that the behavior is introduced by the kernel that was also updated. Here is the important line from /var/log/dpkg.log:

upgrade linux-generic-hwe-20.04:amd64 5.13.0.35.40~20.04.20 5.13.0.39.44~20.04.24

All other upgraded packages are unlikely to have anything to do with it. I tested many of the solutions found on the internet like:

• killing and restarting pulseaudio
• removing the .config/pulse directory
• forcibly killing and restarting alsa
• rebooting several times in between

Nothing of that helped. Would anyone have an official bug-report or a solution?

1 Answer

The one solution that worked in the end was upgrading the kernel to an oem version using

sudo apt-get install linux-oem-20.04d

After the upgrade, I'm running

Kernel: 5.14.0-1031-oem x86_64 bits: 64 Desktop: Gnome 3.36.9 Distro: Ubuntu 20.04.4 LTS (Focal Fossa)