Method of suppressing undesired noise in a hearing aid

1. A method of suppressing undesired noise in a hearing aid comprising a handheld unit in which a microphone is integrated, the hearing aid further comprising another microphone located externally of the handheld unit and connected thereto, the method including the steps of:

a) receiving analog signals generated by said integrated and said external microphones;

b) converting a signal from an integrated microphone and a signal from an external microphone, respectively, into digital signals;

c) dividing the digital signal from the integrated microphone into frequency sub-bands, and thus obtaining integrated microphone sub-band signals;

d) dividing the digital signal from the external microphone into frequency sub-bands, and thus obtaining external microphone sub-band signals;

e) in each frequency sub-band, computing a current spectral amplitude of the integrated microphone sub-band signal and a current spectral amplitude of the external microphone sub-band signal;

f) computing the ratio of the current spectral amplitude of the external microphone sub-band signal to the current spectral amplitude of the integrated microphone sub-band signal;

g) modifying the integrated microphone sub-band signal according to the calculated ratio;

h) synthesizing a full-band output signal from the integrated microphone sub-band signals.

2. The method according to claim 1 , wherein modifying the integrated microphone sub-band signal includes attenuating this signal in each sub-band in which said ratio of the current spectral amplitudes exceeds an attenuation threshold.

3. The method according to claim 2 , wherein the attenuation threshold is predefined.

4. The method according to claim 2 , wherein the attenuation threshold is calculated dynamically.

5. The method according to claim 1 , wherein modifying the integrated microphone sub-band signal includes mixing this signal with the external microphone sub-band signal in each sub-band in which said ratio of the current spectral amplitudes exceeds a substitution threshold.

6. The method according to claim 5 , wherein the integrated microphone sub-band signal and the external microphone sub-band signal are mixed by a mixing coefficient calculated according to the ratio of the current spectral amplitudes, and the substitution threshold.

7. The method according to claim 5 , wherein the substitution threshold is predefined.

8. The method according to claim 6 , wherein the substitution threshold is predefined.

9. The method according to claim 5 , wherein the threshold is calculated dynamically.

10. The method according to claim 6 , wherein the threshold is calculated dynamically.

11. The method according to claim 2 , wherein, in parallel with the attenuation, the integrated microphone sub-band signal is mixed with the external microphone sub-band signal.

12. The method according to claim 11 , wherein the signals are mixed by a mixing coefficient calculated according to the ratio of the current spectral amplitudes, and a substitution threshold.

13. The method according to claim 12 , wherein the substitution threshold is predefined.

14. The method according to claim 12 , wherein the substitution threshold is calculated dynamically.

15. The method according to claim 1 , wherein the sub-band signals are generated by means of a filter bank.

16. The method according to claim 1 , wherein the sub-band signals are generated by means of Short Time Fourier Transform.

17. The method according to claim 1 , wherein at least one additional microphone is integrated in the handheld unit, a signal from the additional integrated microphone being subjected to operations identical to those which the signal from the integrated microphone is subjected to.

18. The method according to claim 1 , wherein the external microphone is included in a headset connected to the handheld unit.

19. The method according to claim 18 , wherein the headset is connected to the handheld unit by wireless connection.

20. A method of suppressing undesired noise in a hearing aid, said hearing aid comprising a handheld unit, in which a microphone is integrated, and another microphone located externally of the handheld unit and connected thereto, and a processor, the method including the steps of:

(a) receiving analog signals generated by said integrated and said external microphones

(b) converting a signal from the integrated microphone and a signal from the external microphone, respectively, into digital signals;

(c) dividing the digital signal from the integrated microphone into frequency sub-bands, and thus obtaining integrated microphone sub-band signals;

(d) dividing the digital signal from the external microphone into frequency sub-bands, and thus obtaining external microphone sub-band signals;

(e) in each frequency sub-band, computing a current spectral amplitude of the integrated microphone sub-band signal and a current spectral amplitude of the external microphone sub-band signal;

(f) computing the ratio of the current spectral amplitude of the external microphone sub-band signal to the current spectral amplitude of the integrated microphone sub-band signal;

(g) modifying the integrated microphone sub-band signal according to the calculated ratio;

(h) synthesizing a full-band output signal from the integrated microphone sub-band signals, said steps (a)-(h) being performed by said processor.