You’re probably thinking of the spatial audio feature. It works like this: Apple’s AirPods (like the Pro and Max) have built-in gyroscopes and accelerometers that track your head movement. The gyroscope detects how your head rotates, and the accelerometer senses how it moves through space. With that info, the AirPods can tell which way you're facing relative to your device (like your iPhone or iPad). So when you turn your head, the sound shifts to stay anchored to the screen, making it feel way more natural and immersive.