I have done as said by Luke and get the weird sound after change the volume.. Attached the log
-- Highpitched rattling like sound with 5.1 surround configuration https://bugs.launchpad.net/bugs/445849 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs