I like everything about Linux mint except that ferkakte startup chime.
Like nails on chalkboard.
It is Linux and you can change anything you like. Turn it off or replace it...
menu/system settings/sound/sounds
Toggle off.
And if you double click the login sound file there it will open the folder where you want to go root and replace the default sound with an .oga or a .ogg file of your own. :)