Notification

[NamanShukla7]

I don't understand why notification sound 

Come when there is no notification come 

It beep with full volume also 

[Amit_MR]

You mat want to try Goodlock module to track where is the sound and vibration coming from. Module name Notistar.
Sometimes sound may come for an action which is hidden like Maps updating the location shared, or something like that

[NamanShukla7]

Bro how to check it

[Sidhabhi]

Use goodlock app/Nice catch module

Also,try reset apps preferences

Settings>apps>click 3 dots at top>select reset apps preferences