MacworldBack in 2022, Apple added a speaker to the AirPods Pro case to help find it when lost in a couch cushion or under a desk. But for years people have been hearing their cases make sounds all on their own. We finally know whysurprise, its not the case at all.As spotted by MacRumors, Apple has added an explanation for the occasional and unprompted noises made by AirPods. Tucked way down in the Use hearing health features with AirPodsPro2 section of the AirPods User Guide, Apple explains that its not actually the case making a noise but rather the AirPods inside the case:To help ensure that your AirPods microphones and speakers are operating at their best (for example, to help provide high-quality hearing test results), your AirPods may periodically play a quiet chime when theyre in their charging case.Users have wondered what the mysterious sound is, which sounds like a faraway chime as you can hear in the video on this Reddit thread. Its not clear what happens if the AirPods discover theyre not operating at their best, but they would presumably send an alert to your iPhone to let you know.Apple added hearing protection features to the AirPods Pro, which includes the high-quality hearing test described in Apples support note. Its not clear whether Apple plans to bring it to other models with noise-cancellation, including the AirPods 4 and AirPods Max.