Getting a repeating, white-noise like "tik tok" from speakers

[Ian Bruntlett]

This bug appears on 20.04 and 20.10

I believe it is a kernel bug.

Currently reporting from Ubuntu 20.10 (beta), having updated packages.
Kernel is x86_64, 5.8.0-21

It can be mitigated by the echo command,namely:
echo -e "\a\a\a"

So I wrote a small shell script to do this:-
#!/usr/bin/env bash
while true
do
    date
    echo -e "\aShh..."
    sleep 5
done

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: linux-image-5.8.0-21-generic 5.8.0-21.22
ProcVersionSignature: Ubuntu 5.8.0-21.22-generic 5.8.13
Uname: Linux 5.8.0-21-generic x86_64
ApportVersion: 2.20.11-0ubuntu49
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: thomas 1239 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri Oct 9 10:45:13 2020
InstallationDate: Installed on 2020-10-09 (0 days ago)
InstallationMedia: Ubuntu 20.10 "Groovy Gorilla" - Beta amd64 (20200930)
IwConfig:
 lo no wireless extensions.

 enp63s0 no wireless extensions.
MachineType: Hewlett-Packard HP Compaq dc5700 Microtower
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.8.0-21-generic root=UUID=9853fe4c-53c3-4680-8919-1e3bd68539d4 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-5.8.0-21-generic N/A
 linux-backports-modules-5.8.0-21-generic N/A
 linux-firmware 1.190
RfKill:

SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/13/2007
dmi.bios.release: 2.4
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 786E2 v02.04
dmi.board.name: 0A60h
dmi.board.vendor: Hewlett-Packard
dmi.chassis.type: 6
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr786E2v02.04:bd04/13/2007:br2.4:svnHewlett-Packard:pnHPCompaqdc5700Microtower:pvr:rvnHewlett-Packard:rn0A60h:rvr:cvnHewlett-Packard:ct6:cvr:
dmi.product.family: 103C_53307F
dmi.product.name: HP Compaq dc5700 Microtower
dmi.product.sku: GE018ET#ABU
dmi.sys.vendor: Hewlett-Packard

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This change was made by a bot.

[Ian Bruntlett (ian-bruntlett)]

I've been downloading and testing Ubuntu STRs (Short Term Releases) for this bug.

Has the bug:-
20.10 (initial testing)
20.04 (initial testing)
19.10 (kernel 5.3.0-18)
19.04 (kernel 5.0.0-13)

Does not have the bug:-
18.10 (kernel 4.18.0-10)
18.04 (kernel 4.15.0-20)

[Ian Bruntlett (ian-bruntlett)]

Have been regularly applying Software Updates with varying degrees of success.

One thing I did see, once, which was interesting. The "Tick Tock" noise happened at the same time that the volume indicator started changing "quiet then loud".

Theory - there are two things changing the sound volume - one quiet, one loud and the ticking noise is happening because of that. So, where does the sound system do that, then? If that can be found, the bug can be killed.

[Ian Bruntlett (ian-bruntlett)]

TL;DR - This bug has been fixed.

Detail...
As of last Saturday (14th November 2020), this bug no longer happens with both Ubuntu 20.04.1 and 20.10. I also noticed that the sound was very much louder than expected from my system - reducing the volume fixed that OK. Tested sound by playing a music video in YouTube. There is the occasional crackle when booting or changing the volume but that is OK.

Ubuntu 20.04.1
Both kernels 5.4.0-53 and 5.4.0-54 were fine.

Ubuntu 20.10
Kernel 5.8.0-28, also fine.