4.2 jelly bean - Android automatically corrects my volume

I have a bit annoying problem. My Android 4.2 Jelly Bean automatically corrects volume down every few minutes. It is rather annoying than a problem.

I tried to find and switch off this functionality, but i was not successful.

Can somebody help me where i can find it and switch it off?

Tablet is not rooted. This occure when I listen Google Play, when I am not listening to music, when i have switched on or off Google Play. It happenes about every 10 minutes or something like that. It happens when plugged headphones via connector or without it. Bluetooth not tested.

Thanks.