Examples that relate to sensor modules removably attachable to wearable audio devices are disclosed. In one example, a removable sensor module comprises a light sensor, a fixed magnet, and a moveable shutter. The moveable shutter comprises a bistable magnet that repels the fixed magnet to urge the shutter into either a privacy position that blocks a field of view of the light sensor or an open position that does not block the field of view of the light sensor.