# US 10,313,785 B2 · Sound processing node of an arrangement of sound processing nodes

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- Number: US 10,313,785 B2
- Document ID: US10313785B2
- Status: Granted
- Kind: B2
- Application number: 15/940,635
- Filed: 2018-03-29
- Published: 2018-09-20
- Granted: 2019-06-04
- Earliest claimed: 2015-10-15
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Yue Lang; Wenyu Jin; Thomas Sherson; Richard Heusdens; Willem Bastiaan Kleijn
- Web page: https://patentgrep.com/patent/US10313785B2

## CPC

- H04R 3/005: {for combining the signals of two or more microphones (specially adapted for hearing aids H04R25/407)}
- G10L 21/0208: Noise filtering
- H04R 1/406: {microphones}
- G10L 21/0232: Processing in the frequency domain
- G10L 2021/02166: {Microphone arrays; Beamforming}
- H04R 2201/401: 2D or 3D arrays of transducers
- H04R 2420/07: Applications of wireless loudspeakers or wireless microphones
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING

## Abstract

A sound processing node for an arrangement of sound processing nodes is disclosed. The sound processing nodes being configured to receive a plurality of sound signals, wherein the sound processing node comprises a processor configured to determine a beamforming signal on the basis of the plurality of sound signals weighted by a plurality of weights, wherein the processor is configured to determine the plurality of weights using a transformed version of a linearly constrained minimum variance approach, the transformed version of the linearly constrained minimum variance approach being obtained by applying a convex relaxation to the linearly constrained minimum variance approach.

## Claims

### Claim 1

A sound processing node for use in an arrangement of sound processing nodes, the arrangement of sound processing nodes configured to receive a plurality of sound signals, wherein the sound processing node comprises:
a processor configured to determine a beamforming signal based on the plurality of sound signals weighted by a plurality of weights, wherein
the processor is configured to determine the plurality of weights using a transformed version of a linearly constrained minimum variance approach, the transformed version of the linearly constrained minimum variance approach being obtained by applying a convex relaxation to the linearly constrained minimum variance approach.

### Claim 2 (depends on 1)

The sound processing node of claim 1, wherein the linearly constrained minimum variance approach is a robust linearly constrained minimum variance approach and wherein the processor is configured to determine the plurality of weights using a transformed version of the robust linearly constrained minimum variance approach parametrized by a parameter α, wherein the parameter α provides a tradeoff between the minimization of the magnitude of the weights and the energy of the beamforming signal.

### Claim 3 (depends on 2)

The sound processing node of claim 2, wherein the processor is configured to determine the plurality of weights using the transformed version of the robust linearly constrained minimum variance approach on the basis of the following equation and constraints:
min
.
⁢
∑
i
∈
V
⁢
∑
l
=
1
M
⁢
1
2
⁢
NM
⁢
t
i
(
l
)
*
⁢
t
i
(
l
)
+
α
2
⁢
w
i
H
⁢
w
i
⁢
⁢
s
.
t
.
⁢
∑
i
∈
V
⁢
D
i
(
p
)
⁢
H
⁢
w
i
=
s
(
p
)
⁢
⁢
∀
p
=
1
,
…
⁢
P
⁢
⁢
⁢
∑
i
∈
V
⁢
t
i
(
l
)
=
∑
i
∈
V
⁢
NY
i
(
l
)
⁢
H
⁢
w
i
⁢
⁢
∀
l
=
1
,
…
⁢
M
,
wherein
wi denotes the i-th weight of the plurality of weights,
Yi(l) denotes the vector of sound signals received by i-th sound processing node,
V denotes the set of all sound processing nodes,
M denotes the total number of microphones of all sound processing nodes, i.e. M=Σi=1Nmi,
N denotes the total number of sound processing nodes,
Di(p) defines a channel vector associated with a p-th direction,
P denotes the total number of directions and
s(p) denotes the desired response for the p-th direction.

### Claim 4 (depends on 2)

The sound processing node of claim 2, wherein the processor is configured to determine the plurality of weights using a further transformed version of the linearly constrained minimum variance approach, the further transformed version of the linearly constrained minimum variance approach being obtained by further transforming the transformed version of the linearly constrained minimum variance approach to the dual domain.

### Claim 5 (depends on 4)

The sound processing node of claim 4, wherein the processor is configured to determine the plurality of weights using the further transformed version of the linearly constrained minimum variance approach on the basis of the following equation using the dual variable λ:
min
.
⁢
∑
i
∈
V
⁢
(
1
2
⁢
λ
H
⁡
(
B
i
H
⁢
A
i
-
1
⁢
B
i
)
⁢
λ
-
λ
H
⁢
C
)
,
wherein the plurality of weights wi are defined by a vector yi defined by the following equation:
yi=[ti(1),ti(2), . . . ,ti(M),wi(1),wi(2), . . . ,wi(mi)]T,
wherein
tj(l)=Σi∈VYi(l)Hwi,
Yi(l) denotes the vector of sound signals received by i-th sound processing node,
V denotes the set of all sound processing nodes,
mi denotes the number of microphones of the i-th sound processing node, and
the dual variable λ is related to the vector yi by means of the following equation:
y*i=Ai−1B*iλ*
A
i
=
diag
⁢
⁢
(
[
1
NM
,
1
NM
,
…
⁢
,
1
NM
,
α
,
α
,
…
⁢
,
α
]
T
)
B
i
=
(
-
1
0
…
0
0
…
0
0
-
1
…
0
0
…
0
⋮
⋮
⋱
⋮
⋮
⋱
⋮
0
0
…
-
1
0
…
0
NY
i
(
1
)
NY
i
(
2
)
…
NY
i
(
m
i
)
D
i
(
1
)
…
D
i
(
P
)
)
C
=
[
0
,
0
,
…
⁢
,
0
,
s
(
1
)
N
,
s
(
2
)
N
,
…
⁢
,
s
(
P
)
N
]
T
wherein
N denotes the total number of sound processing nodes,
M denotes the total number of microphones of all sound processing nodes, i.e. M=Σi=1Nmi,
Di(p) defines a channel vector associated with a p-th direction,
P denotes the total number of directions and
s(p) denotes the desired response for the p-th direction.

### Claim 6 (depends on 4)

The sound processing node of claim 4, wherein the processor is configured to determine the plurality of weights using the further transformed version of the linearly constrained minimum variance approach on the basis of the following equation and the following constraint using the dual variable λ:
min
.
⁢
∑
i
∈
V
⁢
(
1
2
⁢
λ
i
H
⁡
(
B
i
H
⁢
A
i
-
1
⁢
B
i
)
⁢
λ
i
-
λ
i
H
⁢
C
)
s
.
t
.
⁢
D
ij
⁢
λ
i
+
D
ji
⁢
λ
j
=
0
⁢
⁢
∀
(
i
,
j
)
∈
E
,
wherein
P1 Dij=−Dij=±I with I denoting the identity matrix,
E defines the set of sound processing nodes defining an edge of the arrangement of sound processing nodes,
λi defines a local estimate of the dual variable λ for the i-th sound processing node under the constraint that along each edge λi=λj and
the plurality of weights wi are defined by a vector yi defined by the following equation:
yi=[ti(1),ti(2), . . . ,ti(M),wi(1),wi(2), . . . ,wi(mi)]T,
wherein
tj(l)=Σi∈VYi(l)Hwi,
Yi(l) denotes the vector of sound signals received by i-th sound processing node,
V denotes the set of all sound processing nodes,
mi denotes the number of microphones of the i-th sound processing node, and
the dual variable λ is related to the vector yi by means of the following equation:
y*i=Ai−1B*iλ*
and wherein Ai, Bi and C are defined by the following equations:
A
i
=
diag
⁢
⁢
(
[
1
NM
,
1
NM
,
…
⁢
,
1
NM
,
α
,
α
,
…
⁢
,
α
]
T
)
B
i
=
(
-
1
0
…
0
0
…
0
0
-
1
…
0
0
…
0
⋮
⋮
⋱
⋮
⋮
⋱
⋮
0
0
…
-
1
0
…
0
NY
i
(
1
)
NY
i
(
2
)
…
NY
i
(
m
i
)
D
i
(
1
)
…
D
i
(
P
)
)
C
=
[
0
,
0
,
…
⁢
,
0
,
s
(
1
)
N
,
s
(
2
)
N
,
…
⁢
,
s
(
P
)
N
]
T
wherein
N denotes the total number of sound processing nodes,
M denotes the total number of microphones of all sound processing nodes, i.e. M=Σi=1Nmi,
Di(p) defines a channel vector associated with a p-th direction,
P denotes the total number of directions and
s(p) denotes the desired response for the p-th direction.

### Claim 7 (depends on 6)

The sound processing node of claim 6, wherein the processor is configured to determine the plurality of weights on the basis of the primal dual method of multipliers.

### Claim 8 (depends on 7)

The sound processing node of claim 7, wherein the processor is configured to determine the plurality of weights on the basis of a distributed algorithm by iteratively solving the following equations:
λ
i
,
k
+
1
=
(
B
i
H
⁢
A
i
-
1
⁢
B
i
+
∑
j
∈
𝒩
⁡
(
i
)
⁢
R
pij
)
-
1
⁢
(
C
+
∑
j
∈
𝒩
⁡
(
i
)
⁢
(
D
ij
⁢
φ
ji
,
k
+
R
pij
⁢
λ
j
,
k
)
)
φ
ij
,
k
+
1
=
φ
ji
,
k
-
R
pij
⁡
(
D
ij
⁢
λ
i
,
k
+
1
+
D
ji
⁢
λ
j
,
k
)
wherein
(i) defines the set of sound processing nodes neighboring the i-th sound processing node and
Rpij denotes a positive definite matrix that determines the convergence rate and that is defined ∀(i,j)∈E by the following equation:
R
pij
=
1
N
⁢
(
B
i
+
B
j
)
H
⁢
A
i
-
1
⁡
(
B
i
+
B
j
)
.

### Claim 9 (depends on 6)

The sound processing node of claim 6, wherein the processor is configured to determine the plurality of weights on the basis of a min-sum message passing algorithm.

### Claim 10 (depends on 9)

The sound processing node of claim 9, wherein the processor is configured to determine the plurality of weights on the basis of a min-sum message passing algorithm using the following equation:
arg
⁢
⁢
min
⁢
λ
i
⁢
(
1
2
⁢
λ
i
H
(
B
i
H
⁢
A
i
-
1
⁢
B
i
+
∑
j
∈
𝒩
⁡
(
i
)
⁢
m
ji
)
⁢
λ
i
-
N
⁢
⁢
λ
i
H
⁢
C
)
,
wherein mji denotes a message received by the i-th sound processing node from another sound processing node j and wherein the message mji is defined by the following equation:
m
ji
=
B
j
H
⁢
A
j
-
1
⁢
B
j
+
∑
k
∈
𝒩
⁡
(
j
)
,
k
≠
i
⁢
m
kj
.
wherein (j) defines the set of sound processing nodes neighboring the j-th sound processing node.

### Claim 11 (depends on 1)

The sound processing node of claim 1, wherein the linearly constrained minimum variance approach is based on a covariance matrix R and wherein the processor is configured to approximate the covariance matrix R using an unbiased covariance of the plurality of sound signals.

### Claim 12 (depends on 11)

The sound processing node of claim 11, wherein the unbiased covariance of the plurality of sound signals is defined by the following equation:
Q
=
1
M
⁢
∑
l
=
1
M
⁢
Y
(
l
)
⁢
Y
(
l
)
⁢
H
,
wherein
Yi(l) denotes the vector of sound signals received by i-th sound processing node and
M denotes the total number of microphones of all sound processing nodes.

### Claim 13 (depends on 1)

A sound processing system comprising a plurality of sound processing nodes according to claim 1, wherein the plurality of sound processing nodes are configured to exchange variables for determining the plurality of weights using a transformed version of the linearly constrained minimum variance approach.

### Claim 14

A method of operating a sound processing node in an arrangement of sound processing nodes, the sound processing nodes configured to receive a plurality of sound signals, wherein the method comprises:
determining a beamforming signal on the basis of the plurality of sound signals weighted by a plurality of weights by determining the plurality of weights using a transformed version of a linearly constrained minimum variance approach, the transformed version of the linearly constrained minimum variance approach being obtained by applying a convex relaxation to the linearly constrained minimum variance approach.

### Claim 15

A nontransitory computer-readable medium including computer-executable instructions for execution on a sound processing node, such that when the computer-executable instructions are executed by the sound processing node a method is carried out comprising:
determining a beamforming signal on the basis of the plurality of sound signals weighted by a plurality of weights by determining the plurality of weights using a transformed version of a linearly constrained minimum variance approach, the transformed version of the linearly constrained minimum variance approach being obtained by applying a convex relaxation to the linearly constrained minimum variance approach.