Enderdragon hurting Enderman will make stare sound

When an enderdragon attacks a enderman, the stare sound will play.

What I expected to happen:
-The enderman were (silently) mad at the ender dragon.

What actually happened:
-The enderman made the "stare" noise and started to attack the enderdragon.

Steps to reproduce:
1. Go to the end.
2. Walk around on the end stone near enderman.
3. Have the enderdragon charge for you.
4. Let the enderdragon attack the enderman.
5. Hear the noise.