When most people use their AirPods, they're using them for their audio input — they listen to a podcast, a phone call, some music. A new study from Apple's Machine Learning Institute took a different tack and found what was useful in an AirPod wearer's audio output, or at least one aspect of it.

The study suggests that AirPods are capable of keeping track of a user's respiratory rate by monitoring the sound of their breaths in the AirPods' microphones, a prospect that has huge implications in the realm of wearable health products. Typically, tracking diseases and conditions that affect respiratory health require in-person consultations, but AirPods offer an option to track individuals' breathing remotely.

According to the study, "data was collected from 21 individuals using microphone-enabled, near-field headphones before, during, and after strenuous exercise. Respiratory rate was manually annotated by counting audibly perceived inhalations and exhalations." They also used a memory network to overlay different audio conditions over their subjects' breathing to simulate noise to test if the respiratory rates were detectable in a variety of indoor and outdoor situation and concluded that "audio can be a viable signal for passively estimating RR [respiratory rate]" in louder situations.

This isn't the first time Apple products have been studied for their potential use in keeping an eye on respiratory health. Apple Watches updated to watchOS 7 can also keep track of a user's breathing as an optional part of the sleep metrics section of the health app. In that case, the number of breaths someone takes is measured by the watch's built-in accelerometer and has nothing to do with audio input.

Another study published in Nature Biomedical EngineeringNature Biomedical Engineering concluded that smartwatch data on respiratory rate was valuable in catching coronavirus infections, and that "63% of the COVID-19 cases [in the study] could have been detected before symptom onset" given breathing data from a subject's wearable.

Apple is constantly finding new ways to use its technology to monitor users' health, and at one point reportedly considered operating its own brand of primary care clinics. Apple disputes that particular rumor, but with this new study it's possible that AirPods have a future as a clinical tool in legitimate health settings instead of just being a convenient way to listen to some tunes.