You’ve just boarded your flight and have made your way to your seat. You adjust the air nozzle above you, twisting it open. It’s summer, after all, and you just carried a roller bag and a personal item through the airport and onto the plane. It’s time to cool off! The boarding door closes, your plane begins pushing back, and then, out of nowhere, the cabin becomes noticeably quieter as the whooshing noise of air disappears.