Enderman screams at me when I look at them in creative mode

When I look at an enderman in the Nether without a jack-o-lantern they scream at me even though I'm in creative. Their mouths stay closed and they act normal, it's just the sound affect. It will continue at the same volume no matter how far I go for about twenty seconds. It sounds sort of distorted, though that might just be my earbuds since they're not the highest quality.