If you check "Custom sound" and specify a sound, that sound is played *in addition* to the system's horrible pcspkr beep noise, rather than replacing it. It should replace it, as there's not much point in playing both.
...On X11 at least; on Wayland I hear nothing at all when I do something that plays the audible bell, like searching for "kjfdslkjdsflkjs" in Firefox. That's probably a separate issue.
Git commit 9e8f737280f5f5b910498e08734c9579e0df14b7 by Nicolas Fella. Committed on 19/05/2024 at 13:52. Pushed by nicolasfella into branch 'master'. [kaccess] Always suppress audible X11 bell X11 by default produces a horrible beep, which we allow to override with a custom sound. The current code however only suppresses the default beep if 'Audible bell' is disabled, not when a custom sound is enabled. Always disable it so that we get full control over the sound Related: bug 381887 M +6 -10 kaccess/kaccess.cpp https://invent.kde.org/plasma/plasma-desktop/-/commit/9e8f737280f5f5b910498e08734c9579e0df14b7