A method of operating a hearing system comprising a first hearing device and a second hearing device, includes: obtaining sensor data, the sensor data comprising first sensor data representing first physiological data and second sensor data representing second physiological data, where the first sensor data comprises or is indicative of first sensor signal from the first hearing device configured to be arranged at a first ear of a user, and the second sensor data comprises or is indicative of second sensor signal from the second hearing device configured to be arranged at a second ear of the user； comparing the first sensor data and the second sensor data； determining a first parameter based on a result from the act of comparing the first sensor data and the second sensor data； and outputting a first output signal indicative of the first parameter.
