An elk glunk comes deep inside a bull elks throat. The sound is made when an elk has smelled an elk in estrus. Humans very rarely hear it. a YouTube search for elk glunking will give you very little.
I found a great video of an elk glunking with a fantastic end. The hunters are filming as the elk comes charging in, glunking and bugling. The video’s end shows the elk walk toward the man holding the camera and seemingly lunge at him before running away. This elk is clearly sexually frustrated like a highschool boy unable to get laid.