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I've got a lab for high school students, and I'd like to disable audio altogether on the lab computers.

Any suggestions? I've been looking at alsa force-unload, but that only kills processes that are currently using the sound card. When I reload the browser and hit YouTube, sound comes back.

Basically, I want to unload sound from the kernel ...but easier than that.

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6
  • Don't if it would work but would think if you disable/delete or blacklisted the audio/sound drivers in kernel. Would need to be root to disable/enable. Easiest way would be to set sound to mute in settings, but anybody can do/undo that. I am not good enough to explain how.
    – crip659
    Sep 24, 2019 at 22:21
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    Maybe put blacklist snd in a file /etc/modprobe.d/blacklist-snd.conf? AFAIK all the snd modules depend on it (and it depends on soundcore -- see modinfo snd, so perhaps that's the one to blacklist) and I think it's responsible for loading up the sound cards, so in theory without it you shouldn't have any sound possible (unless someone has sudo on modprobe). {Argh, you beat me too it!}
    – pbhj
    Sep 24, 2019 at 23:12
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    Cut the speaker wire :) KISS
    – EODCraft Staff
    Sep 25, 2019 at 6:58
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    Is it possible to disable soundcards in UEFI? My PC allows that.
    – user3518753
    Sep 26, 2019 at 9:54
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    @EODCraftStaff or plug in a dummy headphone plug.
    – rackandboneman
    Sep 27, 2019 at 9:15

4 Answers 4

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35

All right, so blacklisting the sound related modules worked. Thanks to this post:

http://www.pc-freak.net/blog/disabling-sound-kernel-modules-debian-ubuntu-gnu-linux-servers/

The details of the fix:

edit /etc/modprobe.d/snd-blacklist.conf and add these entries (from a Dell standalone pc with 18.04)

blacklist soundcore
blacklist snd
blacklist snd_pcm
blacklist snd_hda_codec_hdmi
blacklist snd_hda_codec_realtek
blacklist snd_hda_codec_generic
blacklist snd_hda_intel
blacklist snd_hda_codec
blacklist snd_hda_core
blacklist snd_hwdep
blacklist snd_timer
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16

A hardware solution: insert a mini-jack connector in the sound output port, but only a connector, without any wire or speaker on it. This has worked for me since the 80's to silence the Mac's otherwise beautiful power-on ding.

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  • 2
    As a more permanent (and gross solution), put hot glue in the jack. I don't know what OP's use-case is but if the problem is kids plugging their own things in (for whatever reason) then this answer won't be enough.
    – Captain Man
    Sep 25, 2019 at 14:37
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    @CaptainMan Hot glue alone won't make the computer route audio to the jack. But you could glue in a jack.
    – Reinstate Monica
    Sep 25, 2019 at 15:28
  • @Solomonoff's Secret good point. I wasn't thinking about built-in speakers.
    – Captain Man
    Sep 25, 2019 at 15:46
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    I used to use this trick in the OP's situation (a lab of computers in a high school class). Of course, I was a student in the class, and was booting up a MacPlus so I could play Risk in drafting class.
    – Joe
    Sep 25, 2019 at 16:25
4

A simple solution would be removing the alsa drivers, i.e.:

sudo apt-get remove --purge alsa
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  • 1
    That could easily be reversed accidentally by some later installation command, right?
    – leftaroundabout
    Sep 26, 2019 at 10:23
  • I guess everything can be reversed later. This is just a quick solution for OP's problem, not a "cripple my sound forever" kind of answer.
    – Pedro Lobito
    Sep 27, 2019 at 5:02
  • Sure, but my point is this will quite likely be reversed inadvertently, namely when installing some package which happens to depend on alsa.
    – leftaroundabout
    Sep 27, 2019 at 8:34
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This seems to work. Edit the file /etc/pulse/client.conf

Change the line:

; autospawn = yes

to

autospawn = no

And

; daemon-binary = /usr/bin/pulseaudio

to

daemon-binary = /usr/bin/pulseaudio

Reboot.

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    Every user could override the settings in /etc/pulse/cliet.conf with his/her own settings in ~/.config/pulse/client.conf, please take a look at man pulse-client.conf.
    – mook765
    Sep 24, 2019 at 22:38
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    So after this change, audio is still playing -- there are just no audio controls any more so volume is 100% . Thanks for the suggestion though. I think alsa just took over when pulse went away.
    – ether_joe
    Sep 24, 2019 at 22:55

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