Sony ULT WEAR Quick Start Manual page 17

Note
In the following cases, wearing detection may react incorrectly. When you are not using the headset, turn off the headset.
With the headset around your neck, your chin goes into the housing
Your hand is placed inside the earpad of the left unit.
The headset is inside a container such as a bag.
The headset is hanging on the edge of something such as a bag.
The headset is on a surface such as a desk.
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