Basically sometimes sound will glitch and player will hear eating\drinking\reloading sound even though there's nobody next to him. Happened even in the open field, so I'm 100% positive that it's not me imagining things. Sound just glitches and the source appears to be somewhere next to the player. Distance to the source seems to be random as the the bug itself. Frequency of the sound is purely random. It seems to me that you can actually hear other players eating\drinking\reloading no matter where they are at the map sometimes. This would explain why the frequency and the source of the sound are so random.
In some of the cases players can become the source of the glitched sound. Happened to the friend of mine. After he changed the mag, I could him reloading every 2-3 minutes even though he wasn't actually reloading his weapon.