No sound suddenly while playing

[Sirins]

Hello there,

I just bought this game for a while.
Recently when i was playing, the sound suddenly disappeared,
I tried to check the setting, but it was fine. 
I needed to come back to home page (means click home on tablet) and re-entered game (not restart), then sound appeared. 
But problems was still there, after playing for a while, it happened again and again.
But I tried to playing on my phone, it worked fine.

Could u plz help me to eliminate to problem, I dont want to play on a such small screen.

Here are my Tablet Info.
Acer:A3-A30
Android version : 5.0.2

Thanks!