cannot get rid of random notification sounds on my Note 3

[Unregistered]

I have tried removing recently installed apps. Turning off notification sounds on currently installed apps.
But I still get random unwanted sounds or vibrations (depending on what I have set as default) all day and night. I am very concerned that my privacy & my phone is compromised or infected.
Anyone or there know of an actual solution? Much appreciated.

 

[B. Diddy]

Welcome to Android Central! Do you have Yahoo Mail installed? That's a frequent culprit.

Are the notification sounds all the default one, or are they different? NFC can sometimes cause tones if the chip detects another NFC chip nearby.