How AirPods track your head position

Compatible AirPods can send head-motion updates to an app through Apple's Core Motion framework. A posture app compares those readings with a position you calibrated earlier and decides when to remind you.

What the headphones measure

An accelerometer senses acceleration, including gravity. A gyroscope senses rotation. The system combines sensor readings into an estimate of orientation before the app receives it. Apple's headphone-motion documentation describes the interface available to developers.

That is useful information about your head. It cannot show the position of your shoulders, lower back or pelvis. The distinction matters whenever an app describes its output as posture tracking.

Pitch, roll and yaw

• Pitch describes tipping your head forward or back.
• Roll describes leaning your head toward a shoulder.
• Yaw describes turning left or right.

Poise uses head tilt relative to your baseline as a cue for its reminders. A head held level does not establish that the rest of your body is upright. Two people can also hold their heads at the same angle while sitting quite differently.

Why calibration matters

Calibration gives the app a reference for how you want to sit. In Poise, sit comfortably upright, look ahead and hold still while the calibration finishes. The app records a baseline and compares later readings with it. See the setup steps.

Recalibrating can help after you change your working position or adjust how the earbuds sit in your ears. It does not turn the sensor into a whole-body posture assessment.

How a reading becomes a reminder

Head movement alone is not enough to decide when to nudge. Poise also considers how long the tilt persists and the settings you selected. Its phone-awareness behavior can hold reminders when head position and phone use match its phone-use conditions. Smart Activity Detection distinguishes stationary, walking and undetermined motion. The walking guide explains the separate walking preferences.

These are interpretations of sensor data, with limits. The app cannot see your screen, identify every activity, or know why you looked down. Different apps can process the same hardware readings differently, so shared sensors do not establish equal detection quality.

Does it work without music?

Poise does not require a song or podcast to be playing. It uses a background audio session to support monitoring and play its reminders. A player indicator can therefore appear even when you have not started music. Read the guide to silence, music and a locked phone.

Battery use and privacy

During testing, Poise made no measurable difference to battery use, even with background sensing enabled. Battery use may vary with your devices and usage.

Your raw motion data stays on-device. Poise also uses subscription services and sends de-identified analytics as explained in its privacy policy. On-device raw processing does not mean no data is collected.

Sources

• Apple: headphone motion services
• Apple: checking motion availability
• Apple: Spatial Audio and head tracking