Hearing device comprising a microphone adapted to be located at or in the ear canal of a user

1. A hearing device configured to be worn by a user, the hearing device comprising

two or more input transducers or two microphones, where said two or more input transducers or two microphones, during use of the hearing device, are arranged with a distance between them; and

a directional system comprising a directional algorithm configured to provide a directional pattern in dependence of said distance,

wherein the hearing device is configured to estimate a current value of said distance, or an equivalent acoustic delay, or beamformer weights of said directional system by measuring a phase difference between signals detected by the two or more input transducers or the two microphones and originating from a sound outlet, and

wherein the phase difference is estimated in dependence on an estimated feedback path from said sound outlet to said two or more input transductors or said two microphones.

2. A hearing device according to claim 1 , wherein the estimated feedback path is estimated by a loop gain estimation algorithm and a signal needed to estimate the loop gain comprises one or more pure tones or broadband noise.

3. A hearing device according to claim 2 , wherein said estimate of the loop gain is provided in real time, in order to adaptively compensate for varying microphone distances during wear of the hearing device.

4. A hearing device according to claim 1 , wherein the directional system provides a directional pattern designed to emphasize sound from one direction and to suppress sound from other directions.

5. A hearing device according to claim 4 , wherein the directional pattern has a cancellation angle, or more cancellation angles, in the rear region that is dependent of the microphone distance.

6. A hearing according to claim 1 , wherein said two or more input transducers or said two microphones includes one microphone located in or at an earpiece and another located elsewhere on the body.

7. A hearing device according to claim 1 , further comprising

a BTE-part adapted to be worn at or behind an ear of a user, and an ITE-part adapted to be located at or in an ear canal of the user, and wherein at least one input transducer is located in the BTE-part,

wherein another input transducer is located in the ITE-part.

8. A hearing device according to claim 1 , wherein said distance is an acoustical microphone distance seen from an external sound field.

9. A hearing device according to claim 1 , further comprising a time to time-frequency conversion unit allowing the processing of signals in the time-frequency domain.

10. A hearing device according to claim 1 , wherein said distance or an equivalent acoustic delay is used to optimize the directional algorithm, a delay and sum algorithm or an MVDR algorithm, for the individual user of the hearing device.

11. A hearing device according to claim 1 being constituted by or comprising a hearing aid, a headset, or an active ear protection device or a combination thereof.

12. A method of operating a hearing device, the hearing device being configured to be worn by a user, the hearing device comprising two or more input transducers, where said two or more input transducers, during use of the hearing device, are arranged with a distance between them, the method comprising:

estimating a current value of said distance, or an equivalent acoustic delay, or beamformer weights of a directional system;

estimating a phase difference between signals detected by the two or more input transducer or two microphones and sound originating from a sound outlet in dependence on an estimated feedback path from the sound outlet to said two or more input transducers or said two microphones; and

providing a directional pattern in dependence of said distance.