An on/off head detection system uses magnetic field intensity to determine a configuration, position, and/or orientation of a headphone. In some implementations, the system may determine whether a headphone is on or off a user's head. The system includes a magnetic field sensor configured to detect a magnetic field emitted by a magnetic field source associated with an earpiece of the headphone. A control module determines an intensity of the magnetic field and whether the intensity of the magnetic field satisfies a threshold. An operational mode associated with the headphone or an associated device is performed in response to the intensity of the magnetic field satisfying the threshold.