it's possible sum 1 made that as an audio file for v.g.sfx and u can buy it and wot not, or it's like the Wilhelm Scream of Toad Forests
Funnilly enough - there's a scene in Wes Anderson's famous train movie, 3 Brothers on a Train Their Dad Is Fucking Deaddo Kid (((Darjeeling Limited))) right before this clip
https://www.youtube.com/watch?v=1j8l...tgMPL1ritSSptz
A guy is walking down the train tracks along the broken down train. A foley effect was used to imitate the sound of someone tapping on the metal railway. I shit you not, it's the same sound effect used for mining a vein of ore in WoW. if you have access to the movie, cheque it oot.