I have the same issue on Xubuntu 18.04 and Debian Stretch. It occurs on a fresh install while watching a video in Firefox. Restarting Pulseaudio does fix the issue for me as well.
I observed that when the problem occurs, I can see multiple instances of speech-dispatcher in Pavucontrol. Whenever I select a different output device for all of them, the crackling disappears. If one of them has the same output device selected as Firefox, the crackling comes back. I could fix the issue by uncommenting the last line (DisableAutoSpawn) in /etc/speech-dispatcher/speechd.conf. I hope it might help. My system: Xubuntu 18.04 CPU: Intel i3-4160 Motherboard: Gigabyte H97-D3HM GPU: Nvidia GTX 1060 3GB -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1739310 Title: Sound crackling in Ubuntu 16.04 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/speech-dispatcher/+bug/1739310/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
