Ender dragon death sound

I was making a map and wanting to have cool effects so i used ender dragons... the death sound was rather annoying cuz i don't want that sound, so i used the silence data tag... i was hoping to get the dragon to die without theat weird death sound but it was still playing... not sure if it was intended but hope it's a bug..
Steps to Reproduce... just use this command, the ender dragon will probably die with the death sound

/summon EnderDragon ~0 ~1 ~0 {CustomName:The Z0NE,CustomNameVisible:0,Attributes:[{Name:generic.maxHealth,Base:1}],NoAI:1,Silent:1}