Hi guys. Been experienced with this problem twice times already so wanna ask here.

My system volume will suddenly drop lower than normal time.
Like normally you listen to music at volume 9, even I put volume 9, the result came out will be like 2 or 3. Which apply to others audio also such as lock screen sound, flip menu sound, sms notification ...

I had to do a restart to solve this problem. Is this some kind like software problem? Thanks.