This video showcases how to produce whistle signals that require more skill than traditional simple signals. You need to use your tongue as shown, or the sound will not come out the same way as demonstrated in this video. The whistle in the video is the Fox 40 Classic. Fox 40 Classic Amazon link: https://amzn.to/45RsJ0F See my review of it here: https://youtu.be/EdoZFUt3i6k See my referee whistle test: https://youtu.be/RF2OUtj445s Instagram: https://www.instagram.com/refereechannel 00:00 - All whistle signals 0:09 - Choppy 00:17 - Quick 00:25 - Wavy 00:36 - Accelerating