In short, turning your sounds off only stops noise you create, for example, if you turn hostile creatures off you don't hear it when you kill endermen, but you DO hear it when players nearby kill them, it's a weird bug.
MC-196175
Enderman noises
Resolved
Awaiting Response
0
Can you provide a screenshot with the debug screen enabled (F3) along with a video of this happening. If the video is to big you can upload it on YouTube as Unlisted then post the link here