Hearing device with optical sensor for determining a tissue property

A hearing system comprising:

• a communication device;
• and
• a hearing device communicatively coupled to the communication device, the hearing device including
• a housing configured to be worn at an ear of a user;
• an output transducer configured to provide an audio signal to the user;
• a light source configured to provide light emitted from a light emission area at the housing, the light illuminating an illumination volume extending into tissue at the ear when the housing is worn at the ear;
• a first photodetector configured to detect a first light intensity of light arriving from a first acceptance volume extending into tissue at the ear when the housing is worn at the ear such that a part of the emitted light scattered by the tissue into the first acceptance volume is contributing to the first light intensity, the first acceptance volume including a first reception area at the housing having a first distance from the light emission area;
• a second photodetector included in the hearing device, the second photodetector configured to detect a second light intensity of light arriving from a second acceptance volume extending into tissue at the ear when the housing is worn at the ear such that a part of the emitted light scattered by the tissue into the second acceptance volume is contributing to the second light intensity, the second acceptance volume including a second reception area at the housing having a second distance from the light emission area different from the first distance;
• and
• a processing unit included in the communications device, the processing unit configured to determine a property of the tissue based on the first light intensity and the second light intensity by taking into account the difference between the first distance and the second distance.

A method of determining a property of a tissue at an ear at which a housing of a hearing device is worn by a user, the method comprising:

• emitting light provided by a light source from a light emission area at the housing, the light illuminating an illumination volume extending into tissue at the ear when the housing is worn at the ear;
• and
• detecting, by a first photodetector, a first light intensity of light arriving from a first acceptance volume extending into tissue at the ear when the housing is worn at the ear such that a part of the emitted light scattered by the tissue into the first acceptance volume is contributing to the first light intensity, the first acceptance volume including a first reception area at the housing having a first distance from the light emission area;
• detecting, by a second photodetector, a second light intensity of light arriving from a second acceptance volume extending into tissue at the ear when the housing is worn at the ear such that a part of the emitted light scattered by the tissue into the second acceptance volume is contributing to the second light intensity, the second acceptance volume including a second reception area at the housing having a second distance from the light emission area different from the first distance;
• and
• determining, based on the first light intensity and the second light intensity, the property of the tissue by taking into account the difference between the first distance and the second distance.