Dual Transfer Function GSC and Application to Joint Noise Reduction and Acoustic Echo Cancellation Gal Reuven Under supervision of Sharon Gannot 1 and Israel Cohen 2 1 School of Engineering, Bar-Ilan University, Ramat-Gan 2 Department of Electrical Engineering, Technion, Haifa February, 2006
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Dual Transfer Function GSC and Application toJoint Noise Reduction and Acoustic Echo
Cancellation
Gal ReuvenUnder supervision of Sharon Gannot1 and Israel Cohen2
1School of Engineering, Bar-Ilan University, Ramat-Gan2Department of Electrical Engineering, Technion, Haifa
Application: joint noise reduction and echo cancellation
• M ≥ 3 microphones
• One desired speech signal
• One competitive speech signal
(echo)
• One directional/ambient noise signal
• Arbitrary acoustic transfer functions
(ATFs)
MICROPHONES ARRAY
AMBIENT NOISE
DESIRED SPEECH SIGNAL
REMOTE SPEECH SIGNAL
NOISE SOURCE
SPEECH ENHANCEMENT
SYSTEM
zm(t) = am(t) ∗ s1(t) + bm(t) ∗ e(t) + nm(t)
m = 1, . . . , M
25
DTF-GSC AND APP. TO JOINT NR AND AEC Application
Cascade scheme
• AEC-BF: multichannel AEC followed by beamformer
– The beamformer inputs contain less echo– The multichannel AEC deteriorates due to noise
• BF-AEC: beamformer followed by single channel AEC
– AEC contains less noise in its input– The beamformer suppresses echo, although AEC has better
performance– AEC suffers from fast variations in echo path due to the beamformer
26
DTF-GSC AND APP. TO JOINT NR AND AEC Application
TF−GSC
∑
∑
∑
U2(t, ejω)
U3(t, ejω)E(t, ejω)
ZM (t, ejω)
Z2(t, ejω)
Z1(t, ejω)
GE2
(t, ejω)
GE1
(t, ejω)
GNM (t, ejω)
GN3
(t, ejω)
GN2
(t, ejω)
ZAECM (t, ejω)
ZAEC2
(t, ejω)
ZAEC1
(t, ejω)
Y (t, ejω)
−
GEM (t, ejω)
+
−
+
∑
∑
YMBF(t, ejω)
−
∑
+
UNM (t, ejω)
H†
W†0
YNC(t, ejω)
−
+
27
DTF-GSC AND APP. TO JOINT NR AND AEC Application
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TF−GSC
∑
∑
H†
Z1(t, ejω)
Z2(t, ejω)
W†0
U2(t, ejω)
U3(t, ejω)
UM (t, ejω)
YNC(t, ejω)
ZM (t, ejω)
E(t, ejω) GE(t, ejω)
GN2
(t, ejω)
GN3
(t, ejω)
GNM
(t, ejω)
YMBF(t, ejω)
∑
−
Y (t, ejω)
−
∑
+
YBF (t, ejω)
+
28
DTF-GSC AND APP. TO JOINT NR AND AEC Application
ETF-GSC scheme
• Matched beamformer (MBF)
– Maintains desired signal
• Blocking unit (BU)
– Blocks both desired and echo signals
• Adaptive noise and echo canceller (ANEC)
– Noise canceller and echo canceller work in parallel– Echo reference signal is used to create more interference reference
signals to the ANEC
29
DTF-GSC AND APP. TO JOINT NR AND AEC Application
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∑
∑
E(t, ejω)
∑
−
+
U′
3(t, ejω)
U′
M(t, ejω)
GNM (t, ejω)
GN3 (t, ejω)
GN2 (t, ejω)
GEM (t, ejω)
GE2 (t, ejω)
GE1 (t, ejω)
∑
Y (t, ejω)
YEC(t, ejω)
∑
F†0
YNC(t, ejω)
Z1(t, ejω)
Z2(t, ejω)
Z3(t, ejω)
ZM (t, ejω)
UM (t, ejω)
U3(t, ejω)
U2(t, ejω)
−
+
H†
F†0
YMBF(t, ejω)
∑
H†
∑−
+
+
−
U′
2(t, ejω)
GH2 (t, ejω)
GH3 (t, ejω)
GHM (t, ejω)
30
DTF-GSC AND APP. TO JOINT NR AND AEC Application
ETF-GSC scheme
• Estimation
– MBF estimation is done as in the TF-GSC (during single talk)– BM estimation is done as in the TF-GSC (during single talk)– Noise canceller adapts during noise only frames– Echo canceller adapts during echo frames
31
DTF-GSC AND APP. TO JOINT NR AND AEC Application
Performance evaluation
Input Tested algorithm Echo suppression Noise reductionSNR SER AEC BF Total Total