In the world of crispness, it’s all about the bubbles. Or at least, the sound of bubbles popping. Studies at Oxford University have shown that when we bite into a surface filled with small brittle cells, each fracture releases a quick burst of high-frequency sound. The more fractures in a bite, the more bursts of sound, and the more crispy the food seems to be. So how do we make things super crispy? Why, we add bubbles. Through carbonation to be exact. Let’s try it out with onion rings.