When I switch to another game without closing Minecraft completely, and go back to Minecraft, all the sound is gone.

I'm playing Minecraft and everything is running normally and I quickly go to another app without closing Minecraft. When I was done , I went back to Minecraft and the normal white loading screen pops up. When it was finished loading I went on playing the game and the sound completely dissapeared. I checked in the settings if I didn't accidentally put the sound off but it was on its loudest. I had to completely restart the game for my sound to come back on. This bug happened countless times before and it's really getting quite irritating.