The following code is used in src/modules/x11/module-x11-bell.c to disable the audible bell:

 > XkbChangeEnabledControls(pa_x11_wrapper_get_display(u->x11_wrapper), XkbUseCoreKbd, XkbAudibleBellMask, 0);

..after the following code, which is meant to re-enable/reset it after the X client quits:

 > auto_ctrls = auto_values = XkbAudibleBellMask;
 > XkbSetAutoResetControls(pa_x11_wrapper_get_display(u->x11_wrapper), XkbAudibleBellMask, &auto_ctrls, &auto_values);


But this either has a bug somewhere or just does not work as expected.

I am not sure where / how the (wrapped) X client is supposed to get closed. 


TEST CASE:
1. Add "autospawn=no" to ~/.pulse/client.conf
2. Kill pulseaudio: pulseaudio -k
3. Start a new X session, and/or make sure that the audible bell is enabled, e.g. "xset b 100". You can use printf '\a' in a terminal to trigger it.
4. Start pulseaudio and load the x11-bell module:
   > pactl load-module module-x11-bell sample=bell.ogg
   > pactl upload-sample /usr/share/sounds/gnome/default/alerts/glass.ogg bell.ogg

5. The bell should either get routed through PA now (if you have a "bell" sample uploaded), fallback to the speaker or you will hear nothing (Bug 58930).
6. Unload the module again:
   > pactl unload-module module-x11-bell

EXPECTED:
Now the default X bell should be enabled again.

ACTUAL RESULT:
Nothing happens on a bell event now: pulseaudio is stopped and the previous state has not been restored.


A workaround is to (unconditionally) enable the X bell again when the x11-bell module gets unloaded, but then it might get enabled, although it wasn't before:

    XkbChangeEnabledControls(pa_x11_wrapper_get_display(u->x11_wrapper), XkbUseCoreKbd, XkbAudibleBellMask, XkbAudibleBellMask);