Method for reducing noise in an input signal of a hearing device as well as a hearing device
View Patent ↗A method for reducing noise in an input signal ( 110 ) of a hearing device comprising a transfer function (H) as well as a hearing device is disclosed. The method comprises the steps of: capturing first and second acoustic signals by first and second acoustic-electric converters ( 1, 2 ), providing first and second input signals ( 110, 311 ) by the first and the second acoustic-electric converters ( 1, 2 ), deriving an information signal ( 410 ) by using the first and the second input signals ( 110, 311 ), deriving an information signal estimate (S) from the information signal ( 410 ), deriving a noise signal ( 411 ) by using the first and the second input signals ( 110, 311 ), deriving a noise signal estimate (N) from the noise signal ( 411 ), generating instantaneous coefficients ( 412, 312 ) for the transfer function (H) by using the information signal estimate (S) and the noise signal estimate (N), applying the transfer function (H) to the first input signal ( 110 ) or to a processed first input signal ( 410 ) generating an output signal ( 111 ), and feeding the output signal ( 111 ) to an electro-acoustic converter ( 5 ) of the hearing device.
1. A method for reducing noise in an input signal ( 110 ) of a hearing device comprising a transfer function (H), the method comprising the steps of:
capturing first and second acoustic signals by first and second acoustic-electric converters ( 1 , 2 ),
providing first and second input signals ( 110 , 311 ) by the first and the second acoustic-electric converters ( 1 , 2 ),
deriving an information signal ( 410 ) by using the first and the second input signals ( 110 , 311 ),
deriving an information signal estimate (S) from the information signal ( 410 ),
deriving a noise signal ( 411 ) by using the first and the second input signals ( 110 , 311 ),
deriving a noise signal estimate (N) from the noise signal ( 411 ),
generating instantaneous coefficients ( 412 , 312 ) for the transfer function (H) by using the information signal estimate (S) and the noise signal estimate (N),
applying the transfer function (H) to the first input signal ( 110 ) or to a processed first input signal ( 410 ) generating an output signal ( 111 ), and
feeding the output signal ( 111 ) to an electro-acoustic converter ( 5 ) of the hearing device.
2. The method of claim 1 , wherein the processed first input signal is the information signal ( 410 ).
3. The method of claim 1 or 2 , wherein the information signal ( 410 ) is obtained by a beamformer algorithm from a front facing cardioid in relation to a hearing device user.
4. The method of claim 1 , wherein the noise signal ( 411 ) is obtained by a beamformer algorithm from a back facing cardioid in relation to a hearing device user.
5. The method of claim 1 , wherein the steps of deriving the information signal estimate (S) and/or the noise signal estimate (N) are obtained by one of the following calculations applied to the information signal ( 410 ) and/or the noise signal ( 411 ), respectively:
calculation of power spectrum density;
calculation of absolute value;
calculation of squared absolute value;
calculation of logarithm.
6. The method of claim 5 , wherein the step of generating instantaneous coefficients ( 412 , 312 ) for the transfer function (H) is performed by using a Wiener filter using the information signal estimate (S) and the noise signal estimate (N) in particular according to the following formula:
W
f
[
k
]
=
S
f
[
k
]
2
S
f
[
k
]
2
+
N
f
[
k
]
2
wherein f denotes a frame instance, k denotes a frequency band, S[k] corresponds to the information signal ( 410 ) and N[k] corresponds to the noise signal ( 411 ).
7. The method of claim 1 , wherein the step of generating instantaneous coefficients ( 412 , 312 ) for the transfer function (H) is performed by using a Wiener filter using the information signal estimate (S) and the noise signal estimate (N) in particular according to the following formula:
W
f
[
k
]
=
S
f
[
k
]
2
S
f
[
k
]
2
+
N
f
[
k
]
2
wherein f denotes a frame instance, k denotes a frequency band, S[k] corresponds to the information signal ( 410 ) and N[k] corresponds to the noise signal ( 411 ).
8. The method of claim 7 , further comprising the step of averaging the generated instantaneous coefficients ( 412 ).
9. The method of claim 1 , further comprising the step of averaging the generated instantaneous coefficients ( 412 ).
10. A hearing device comprising:
at least two acoustic-electric converters ( 1 , 2 ) providing at least first and second input signals ( 110 , 311 ),
a receiver ( 5 );
a filter unit ( 101 ) having a transfer function (H), the filter unit ( 101 ) being operatively connected in-between the at least two acoustic-electric converters ( 1 , 2 ) and the receiver ( 5 ),
characterized by further comprising
a computing unit ( 302 ) having an input side and an output side, with the input side operatively connected to the at least two acoustic-electric converters ( 1 , 2 ), and with the output side operatively connected to the filter unit ( 101 ),
the computing unit ( 302 ) comprising
means for deriving an information signal ( 410 ) by using at least the first and the second input signals ( 110 , 311 ),
means for deriving an information signal estimate (S) from the information signal ( 410 ),
means for deriving a noise signal ( 411 ) by using at least the first and the second input signals ( 110 , 311 ),
means for deriving a noise signal estimate (N) from the noise signal ( 411 ), and
means for generating instantaneous coefficients ( 412 , 312 ) for the transfer function (H) by using the information signal estimate (S) and the noise signal estimate (N).
11. The hearing device according to claim 10 , characterized in that the means for deriving the information signal ( 410 ) by using at least the first and the second input signals ( 110 , 311 ) is operatively connected in-between one of the at least two acoustic-electric converters ( 1 , 2 ) and the filter unit ( 101 ).
12. The hearing device according to claim 10 or 11 , characterized in that the information signal ( 410 ) is obtained by a beamformer algorithm from a front facing cardioid in relation to a hearing device user.
13. The hearing device according to claim 10 , characterized in that the noise signal ( 411 ) is obtained by a beamformer algorithm from a back facing cardioid in relation to a hearing device user.
14. The hearing device according to claim 10 , characterized in that the information signal estimate (S) and/or the noise signal estimate (N) are obtained by one of the following calculations applied to the information signal ( 410 ) and/or the noise signal ( 411 ), respectively:
calculation of power spectrum density;
calculation of absolute value;
calculation of squared absolute value;
calculation of logarithm.
15. The hearing device according to claim 14 , characterized in that the means for generating instantaneous coefficients ( 412 ) for the transfer function (H) in the filter unit ( 101 ) comprises an implementation of a Wiener filter using the information signal estimate (S) and the noise signal estimate (N) in particular according to the following formula:
W
f
[
k
]
=
S
f
[
k
]
2
S
f
[
k
]
2
+
N
f
[
k
]
2
wherein f denotes a frame instance, k denotes a frequency band, S[k] corresponds to the information signal ( 410 ) and N[k] corresponds to the noise signal ( 411 ).
16. The hearing device according to claim 10 , characterized in that the means for generating instantaneous coefficients ( 412 ) for the transfer function (H) in the filter unit ( 101 ) comprises an implementation of a Wiener filter using the information signal estimate (S) and the noise signal estimate (N) in particular according to the following formula:
W
f
[
k
]
=
S
f
[
k
]
2
S
f
[
k
]
2
+
N
f
[
k
]
2
wherein f denotes a frame instance, k denotes a frequency band, S[k] corresponds to the information signal ( 410 ) and N[k] corresponds to the noise signal ( 411 ).
17. The hearing device according to claim 16 , characterized in that an averaging unit ( 406 ) is operatively connected in-between the means for generating instantaneous coefficients ( 312 ) for the transfer function (H) and the filter unit ( 101 ).
18. The hearing device according to claim 10 , characterized in that an averaging unit ( 406 ) is operatively connected in-between the means for generating instantaneous coefficients ( 312 ) for the transfer function (H) and the filter unit ( 101 ).