Twirl this plastic “hose” over your head to hear different tones as the speed changes! It’s a fun science activity that teaches kids (and adults) cool principles relating to air pressure, molecules, and sound in a hands-on way. The free end of the Sound Hose, when twirling, is moving faster than the end in your hand. Because fast-moving molecules have a lower pressure than slow-moving molecules, a pressure gradient is created between the two ends of the hose. Air is sucked through the hose producing a whistling sound. The faster you twirl, the higher pitched the whistle becomes!