so this is where it came from... I'm so happy i found the sound for it I'm on the floor laughing, awesome work Adam you are a great human being for making wooden contraptions and/or basic items!
In the description it says that it was used to communicate over great distances. If you want to know more i would suggest looking up on the history of these bullroarers
This is only the second person out of about 10 that I've seen rapping all that cord around the thing. Most people just make the regular board and use the cord to swing it with
