Guinea Pig Sounds and What They Mean

This are the different noises guinea pigs make and their meaning. This is the way that I interpret the noises. I did do research on the purr people said it was a rumble (scared, afraid, annoyed) but how do you prove that when these guineas are laying down and eating grass (they LOVE grass and laying down is a sign of relaxation) AND PURRING (rumbling, whatever you want to call it).