https://en.wikipedia.org/wiki/Tettigoniidae

Ryan received a rattlesnake call this morning that turned out to most probably be someone hearing an insect. While considering likely suspects, I remembered the interesting sound of Bush Crickets and Katydids. These are not much like rattlesnake rattling, but could possibly be confused with it by people who are a bit paranoid, or trying to be ‘proactive’ without actually understanding the animals they are concerned about.