My xB is the only car I have ever had that has a high frequency "buzzer" instead of a "beep-beep" when lights are left on and ignition switch turned off. 
Sadly, due to too much drumming in a band plus many years, I am unable to hear that frequency.  Anybody know of a possible swap-out of the current high frequency buzzer for one  at a lower frequency or with  the standard "beep-beep" signal. Dealership offers only sympathy.