Hello, welcome to the Samsung community. I understand your concerns with the random alarm sounding and I will be more than happy to take a look into this with you.
We would recommend placing the device in Safe Mode to determine which third party app is causing the random alarm sound.
To place your device in Safe Mode:
Power off your device
Turn on the device, when the Samsung logo appears press and hold the volume down button.
Safe Mode will appear in the bottom left corner of the screen (If Safe Mode does not appear repeat the previous steps).
Once you are in Safe Mode you can remove the third party app causing the alarm sound. Start by removing apps that were updated when the alarm sound started.
To exit Safe Mode, simply restart your phone normally