Details behind Apple's 'Skin-Detect Sensor' introduced with their 3rd Gen AirPods have been revealed in a new Patent
Apple introduces new Skin-Detect Sensors with their 3rd gen AirPods as listed on their sensors list. In Apple’s October 2021 press release about their 3rd gen AirPods they singled out this new sensor: “A new skin-detect sensor accurately discerns if AirPods are in the ear — versus in a pocket or on a table — and pauses playback when removed." This week a detailed patent from Apple covers Apple's newest sensor for AirPods
Source: patentlyapple.com