Disable ugly pc-speaker sound in Slim auth failure

[znavko]

Hello! Please, what should I use in config.scm for disable pc-speaker sound 
while authorize in Slim and have an error in password?


$ cat /etc/config.scm
...
(services (cons* 
...
 (modify-services %desktop-services

                                (slim-service-type config =>
                                              (slim-configuration
                                               (inherit config)
                                               (startx
                                                (xorg-start-command
                                                 #:configuration-file
                                                 (xorg-configuration-file
                                                  #:extra-config
                                                  '(
"Section \"InputClass\"
        Identifier \"touchpad\"
        Driver \"libinput\"
        MatchIsTouchpad \"on\"
        Option \"Tapping\" \"on\"
EndSection"
                                 ))))))
)  ;end of modify-services 2nd
...
)