Method of operating a hearing aid, and hearing aid

1. A method of operating a hearing aid having a first input transducer for generating a first input signal from an ambient sound signal, a second input transducer for generating a second input signal from the ambient sound signal, and an output transducer, the method which comprises:

assigning a first direction to a first useful signal source and assigning a second direction to a second useful signal source that is spatially separated from the first useful signal source;

forming, based on the first input signal and the second input signal, a first reference signal oriented in the first direction and a second reference signal oriented in the second direction;

forming an output signal by superimposing the first reference signal and the second reference signal; and

converting the output signal into a sound signal by the output transducer of the hearing aid.

2. The method according to claim 1 , which comprises, for superimposing the first and second reference signals, defining linear factors as a function of frequency band for the first reference signal and for the second reference signal.

3. The method according to claim 1 , wherein one or both of the first and second reference signals have a conical or lobe-shaped directional characteristic.

4. The method according to claim 3 , wherein the directional characteristic of the first reference signal and/or of the second reference signal has a maximum sensitivity at a central angle and a sensitivity which is attenuated by at least 3 dB at an angle of deviation of 10° from the respective central angle.

5. The method according to claim 1 , wherein the assigning step comprises determining the first direction and the second direction on a basis of the first input signal and of the second input signal.

6. The method according to claim 5 , wherein:

based on the first input signal and the second input signal, a multiplicity of angle-dependent directional characteristics is formed, in each case having a fixed central angle and a given angular spread;

examining signal components for the individual directional characteristics for a presence of a useful signal from a useful signal source; and

for a first useful signal source identified in a specific directional characteristic, specifying a corresponding central angle as the first direction.

7. The method according to claim 6 , wherein an angular distance between two adjacent directional characteristics with respect to their respective central angles corresponds to half the given angular spread.

8. The method according to claim 6 , which comprises:

defining each of the individual directional characteristics by a notch-shaped sensitivity characteristic, which is defined by at least two conditions, so that in each case the central angle and the angular spread of the sensitivity characteristic are specified by the at least two conditions; and

examining each of the signal components for the individual directional characteristics for the presence of the useful signal based on a relative attenuation due to the sensitivity characteristic.

9. The method according to claim 1 , wherein:

the hearing aid is worn by a user; and

the first input signal and the second input signal are generated on different sides with respect to the head of the user.

10. The method according to claim 1 , wherein a further input transducer generates a further input signal from the ambient sound signal, and the forming step comprises forming the first and second reference signals based on the first input signal, the second input signal and the further input signal.

11. The method according to claim 1 , which comprises:

assigning a further direction to a further useful signal source that is spatially separated from the first useful signal source and the second useful signal source;

forming a further reference signal oriented in the further direction based on the first input signal and the second input signal; and

forming the output signal based on the first reference signal, the second reference signal and the further reference signal.

12. A hearing aid, comprising:

at least one first input transducer for generating a first input signal from an ambient sound signal;

a second input transducer for generating a second input signal from the ambient sound signal;

at least one output transducer; and

a signal processing unit configured for carrying out the method according to claim 1 .