Silant Arm
Specify your car year, brand, model. If your remote system is not provided by manufacturer, then it is possible it support both chirp arm, and silent arm.
Chirp arm will buzz the speaker & flash the signal lights when you arm the system
Silent arm will only flash the signal lights.
You may accidentally press the combination to enable silent arm. Find out which alarm system you have, or check the user manual for your alarm.
Else, sent to accesory shop and pay them for consultation