Blind Audio Source Separation based on Independent ... · ... Blind Audio Source Separation based...

35
ICA2007 Keynote – Blind Audio Source Separation based on Independent Component Analysis Shoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 1 Shoji Makino, Hiroshi Sawada, Shoji Makino, Hiroshi Sawada, and Shoko Araki and Shoko Araki NTT Communication Science Laboratories, Kyoto, Japan Blind Audio Source Separation Blind Audio Source Separation based on based on Independent Component Analysis Independent Component Analysis Participants: 247 Oversea: 119 21 Countries April 1-4, 2003 Nara, Japan General Chair: Shun-ichi Amari(RIKEN) Organizing Chair: Shoji Makino(NTT)

Transcript of Blind Audio Source Separation based on Independent ... · ... Blind Audio Source Separation based...

Page 1: Blind Audio Source Separation based on Independent ... · ... Blind Audio Source Separation based on Independent Component Analysis Shoji Makino, Hiroshi Sawada, and Shoko Araki (NTT

ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 1

Shoji Makino, Hiroshi Sawada, Shoji Makino, Hiroshi Sawada, and Shoko Arakiand Shoko Araki

NTT Communication Science Laboratories, Kyoto, Japan

Blind Audio Source Separation Blind Audio Source Separation based on based on

Independent Component AnalysisIndependent Component Analysis

Participants: 247Oversea: 11921 Countries

April 1-4, 2003 Nara, JapanGeneral Chair: Shun-ichi Amari(RIKEN) Organizing Chair: Shoji Makino(NTT)

Page 2: Blind Audio Source Separation based on Independent ... · ... Blind Audio Source Separation based on Independent Component Analysis Shoji Makino, Hiroshi Sawada, and Shoko Araki (NTT

ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 2

April 15April 15--20, 2007 Hawaii, USA20, 2007 Hawaii, USA

Tutorial Tutorial onon

Audio Source Separation Audio Source Separation based on based on

Independent Component AnalysisIndependent Component Analysis

Organizers: Shoji Makino

Hiroshi Sawada

ShouShou--TokuToku--TaishiTaishi

Could separate ten speeches.

Page 3: Blind Audio Source Separation based on Independent ... · ... Blind Audio Source Separation based on Independent Component Analysis Shoji Makino, Hiroshi Sawada, and Shoko Araki (NTT

ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 3

At a Cocktail PartyAt a Cocktail Party

Reverberation

moreclearly!

Morning!

Hello!!Mixing

When two people talk to a computerWhen two people talk to a computer

Hello!

Morning!

Hello!Hello!

Hello!

Morning!

Morning!

Morning!Morning!Morning!Hello!

Hello!

I cannot understand!

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 4

Reverberation

moreclearly!

Morning!

Hello!!

Target signal must be extracted from mixed signals (source separation)

Mixing

Task of Blind Source SeparationTask of Blind Source Separation

Hello!

Morning!

Hello!Hello!

Hello!

Morning!

Morning!

Morning!

Speech recognition(Robots, Car navi. …) People(TV conferences, Hearing aids, …)

Morning!Morning!Hello!Hello!

Observed signal XSource signal S Separated signal Y

Hello!

Morning!

Separation system WEstimate S1 and S2using only X1 and X2

Y1

Y2

Hello!

Morning!

S1

S2

H11

H21

H12

H22

Model of Blind Source SeparationModel of Blind Source Separation

Mixing system HDelayAttenuationReverberation

Hello!Morning!

Hello!Morning!

X1

X2

W21

W12

W22

W11

Source SIndependent

BlindBlind

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 5

Blind Source Separation using Blind Source Separation using Independent Component AnalysisIndependent Component Analysis

H W

Hello!

Morning!

Observed signals X1and X2 are correlated

Extract Y1 and Y2 so that they are mutually independent

Source signals S1 and S2 are statistically independent

No need for information on the source signals or mixing system(location or room acoustics) ⇒ Blind Source Separation

No need for information on the source signals or mixing system(location or room acoustics) ⇒ Blind Source SeparationNo need for information on the source signals or mixing system(location or room acoustics) ⇒ Blind Source Separation

BlindBlind Source Separation using Source Separation using Independent Component AnalysisIndependent Component Analysis

Unsupervised Learning by ICAUnsupervised Learning by ICA

H11

H21

H22

S1

S2

Mixing system H

Y1W11

W12

W21

W22

H12

X1

X2 Y2

Separation system W

Estimate W so that Y1and Y2 become mutually independent

Source signals S1 and S2 are statistically independent

Observed signal XSource signal S Separated signal Y

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 6

Background TheoryBackground Theory

- Minimization of Mutual Information(Minimization of Kullback-Leibler Divergence)

All solutions areidentical

- Maximization of Non-Gaussianity

- Maximization of Likelihood

Background TheoryBackground Theory

All solutions are identical

),()(),( 21

2

121 YYHYHYYI

ii −=∑

=

Minimization of Mutual Information

Maximization of Non-Gaussianity

Maximization of Likelihood

MarginalEntropy

JointEntropy

MutualInformation

H(・):Entropy

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 7

Background TheoryBackground Theory

- Maximization of Non-Gaussianity

• Make the output pdf away from Gaussian

Central Limit TheoremCentral Limit Theorem

Mix independent components ⇒ Gaussian

Find independent component ⇒ Non-Gaussian

maximization of negentropymaximization of |kurtosis|

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 8

Wave forms

Am

plitu

des

Wave forms

Histograms

Amplitude

Gaussian

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 9

Central Limit TheoremCentral Limit Theorem

Mix independent components ⇒ Gaussian

Find independent component ⇒ Non-Gaussian

Non-Gaussianity measuresNegentropy

Kurtosis

Maximization of NegeMaximization of Negentropiesntropies

00.0120.0250.0870.225Negentropy N

1.411.401.391.331.19Entropy H

Gaussian16821# sources N

)()()( gauss yHxHyN −=

∑=

=n

i ii p

pyH1

1log)(

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 10

Maximization of KurtosisMaximization of Kurtosis

00.390.701.82.1Kurtosis

Gaussian16821N

224 })|{|(3}|{|)( yEyEykurt −=

Background TheoryBackground Theory

- Minimization of Mutual Information(Minimization of Kullback-Leibler Divergence)

• Make the output “decorrelated”

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 11

H(Y2)H(Y1)

H(Y1,Y2)

),()(),( 21

2

121 YYHYHYYI

ii −=∑

=

MarginalEntropy

JointEntropy

MutualInformation

Mutual InformationMutual Information

H(・):Entropy

H(Y2)H(Y1)

H(Y1,Y2)

I(Y1,Y2)Mutual

Information

),()(),( 21

2

121 YYHYHYYI

ii −=∑

=

Mutual InformationMutual Information

H(・):EntropyMarginalEntropy

JointEntropy

MutualInformation

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 12

H(Y2)H(Y1)I(Y1,Y2)=0

Mutual Information

),()(),( 21

2

121 YYHYHYYI

ii −=∑

=

H(Y1,Y2)

Minimization of Mutual InformationMinimization of Mutual Information

H(・):EntropyMarginalEntropy

JointEntropy

MutualInformation

),()(),( 21

2

121 YYHYHYYI

ii −=∑

=

MarginalEntropy

JointEntropy

MutualInformation

∫∫ += 22

211

1 )(1log)(

)(1log)( dY

YpYpdY

YpYp

∫− 2121

21 ),(1log),( dYdY

YYpYYp

∫= 2121

2121 )()(

),(log),( dYdYYpYp

YYpYYp

Kullbuck-LeiblerDivergence

Minimization of Mutual InformationMinimization of Mutual Information

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 13

∫= 2121

212121 )()(

),(log),(),( dYdYYpYp

YYpYYpYYI

MutualInformation

Kullbuck-LeiblerDivergence

- Search for W which minimizes Mutual Information I- Gradient of W can be derived by differenciating I

with W, using y = Wx;

WWW

W T2,1 )( −

∂∂

−∝ΔYYI ( )W(Y)YI ][E Tφ−=

YY(Y)

d)(logd p−=φwhere

Minimization of Mutual InformationMinimization of Mutual Information

How can we separate speech?How can we separate speech?

Diagonalize RY

⎥⎦

⎤⎢⎣

⎡⟩⟨⟩⟨⟩⟨⟩⟨

=2212

2111

)()()()(YYYYYYYY

RY φφφφ

S H X WY1

Y2⟨⋅⟩ averaging operator

)(⋅φ activation function

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 14

0)( 12 =⟩⟨ YYφ0)( 21 =⟩⟨ YYφ

Mutual independence

At the Convergence PointAt the Convergence Point

⎥⎦

⎤⎢⎣

⎡*00*

Average amplitude of Y

111)( cYY =⟩⟨φ 222 )( cYY =⟩⟨φ⎥⎦

⎤⎢⎣

2

1

**c

c

4 equations for 4 unknowns Wij

1

11 d

)(logd)(Y

YpY −=φ

iii WWW Δ+=+1

ii WYYcYY

YYYYcW ⎥

⎤⎢⎣

⎡⟩⟨−⟩⟨

⟩⟨⟩⟨−=Δ

22212

21111

)()()()(

φφφφ

μ 0

⎥⎦

⎤⎢⎣

⎡⟩⟨⟩⟨⟩⟨⟩⟨

=2212

2111

)()()()(YYYYYYYY

RY φφφφ

Y1

Y2

X1

X2

W

ICA Learning RuleICA Learning Rule

Update W so that Y1 and Y2 become mutually independent

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 15

)tanh()( 11 YY =φ

Higher Order Statistics (HOS)

0)( 21 =⟩⟨ YYφ

0)( 21 =⟩⟨ YYφ

Second Second Order StatisticsOrder Statistics vs.vs. Higher Higher Order StatisticsOrder Statistics

Second Order Statistics (SOS)

11)( YY =φ 021 =⟩⟨ YY

0)152

3 2

51

31

1 =⟩+−⟨ YYYY L

for multipletime blocks

nonstationarysources

Tailorexpansion

0)tanh( 21 =⟩⟨ YY

Convolutive mixtureHij are FIR filters > 1000 taps- sounds in a room

Instantaneous vs. ConvolutiveInstantaneous vs. Convolutive

Instantaneous mixtureHij are scalars- sounds with mixer- images- wireless communication signals- fMRI and EEG signals

Hello!

Morning!

S1

S2

H11

H21

H12

H22

Well studied, good results

Difficult problem, relatively new

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 16

Mixing Filters and Separation FiltersMixing Filters and Separation Filters

Y1

Y2

S1

S2

X1

X2

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H11

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H21

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H12

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H22

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W11

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W22

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W21

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W12

Time Domain

Y1

Y2

S1

S2

X1

X2100 200 300 400 500 600 700 800 900 1000

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W21

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W22

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W11

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

W12

Mixing Filters and Separation FiltersMixing Filters and Separation Filters

Time Domain in a Matrix

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H12

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H11

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H21

100 200 300 400 500 600 700 800 900 1000−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

H22

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 17

Time

Time-domain signal

TimeFr

eque

ncy

Frequency-domain time-series signal

Short Time DFT (Spectrogram)Short Time DFT (Spectrogram)

Convolutive mixture in time domain

Multiple instantaneous mixtures in frequency domain

Frequency-domain time-series signal

Freq

uenc

y

Time

4000

0

Observed signal X2

Apply instantaneous ICA approach to each frequency bin

4000

0

Freq

uenc

y

Time

Observed signal X1

Frequency

Frequency Domain BSSFrequency Domain BSS

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 18

Y1

Y2

S1

S2

X1

X2

W11(f)W11(f)W11(f)W11(f)W11(f)

W11(f)W11(f)W11(f)W11(f)W21(f)

W11(f)W11(f)W11(f)W11(f)W12(f)

W11(f)W11(f)W11(f)W11(f)W22(f)

Frequency

Frequency

Frequency

Frequency

Mixing Filters and Separation FiltersMixing Filters and Separation Filters

FrequencyDomainW11(f)W11(f)W11(f)W11(f)H11(f)

W11(f)W11(f)W11(f)W11(f)H21(f)

W11(f)W11(f)W11(f)W11(f)H12(f)

W11(f)W11(f)W11(f)W11(f)H22(f)

Frequency

Frequency

Frequency

Frequency

Y1

Y2

S1

S2

X1

W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)

Frequency

X2

Mixing Filters and Separation FiltersMixing Filters and Separation Filters

FrequencyDomain in many Matrices

W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)W11(f) W12(f)

W21(f) W22(f)H11(f) H12(f)

H21(f) H22(f)

Frequency

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 19

)(ty)(tx

Mixedsignals

Separatedsignals

Separationfilters

Flow of Frequency Domain BSSFlow of Frequency Domain BSSTime domain

ScalingPermutation Spectralsmoothing

Frequency domain

),( tfXSTFT

)( fWICA

separation matrix

)( fWIDFT

)(lw )(lw

Permutation Spectralsmoothing

Physical Interpretation of BSSPhysical Interpretation of BSS

BSS = Two sets of ABF

Page 20: Blind Audio Source Separation based on Independent ... · ... Blind Audio Source Separation based on Independent Component Analysis Shoji Makino, Hiroshi Sawada, and Shoko Araki (NTT

ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 20

Adaptive Beamformer (ABF)Adaptive Beamformer (ABF)

•• StrategyStrategyMinimize the output when only a jammer is active but a target is not active

(b)

•• AssumptionsAssumptionsDirection and absence period of a target is known

Target S1

Jammer S2

C1S1

0Target S1C1S1

⎥⎦

⎤⎢⎣

⎡=⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡c

cHHHH

WWWW

2

1

2221

1211

2221

1211

00

Two Sets of ABFsTwo Sets of ABFs

C1S1S1

S2

(a) ABF for target S1and jammer S2

C2S2

S1

S2

(b) ABF for target S2and jammer S1

⎥⎦

⎤⎢⎣

⎡=⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡c

cHHHH

WWWW

2

1

2221

1211

2221

1211

00⎥⎦

⎤⎢⎣

⎡=⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡c

cHHHH

WWWW

2

1

2221

1211

2221

1211

00

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 21

Blind Source Separation (BSS)Blind Source Separation (BSS)

•• StrategyStrategyMinimize the SOSSOS or HOS of the outputs

•• AssumptionsAssumptionsTwo sources are mutually independent

Hello!

Morning!

C1S1

C2S2

C1S1

C2S2

)()(),()()(

)(),()(),(

*22

*12

*2111⎥⎦

⎤⎢⎣

⎡=

=

=

∗∗

YYYYYYYY

E

kkk

S ωωωωωωωωω

WHΛHWWRWR XY

[ ][ ] [ ] [ ] [ ]( ){ }

0

)(22

22

11221

221

=+++= ∗∗∗∗∗∗

SEbdSEacSSEbcSSEadYYE

( )

• After convergence, the off-diagonal component is

Diagonalization of in BSSDiagonalization of in BSS

= =

0 0(If S1 and S2 are ideally independent)

),( kY ωR

),( kY ωR• The BSS strategy works to diagonalize

00

dc b 0= = a

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 22

=

where

⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡=

⎥⎥⎦

⎢⎢⎣

HHHH

WWWW

dac

b

2221

1211

2221

1211a bc d

BSS SolutionsBSS Solutions

⎥⎦

⎤⎢⎣

⎡=⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡c

cHHHH

WWWW

2

1

2221

1211

2221

1211

00

CASE 1: a=c1, c=0, b=0, d=c2

⎥⎦

⎤⎢⎣

⎡=⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡0

02

1

2221

1211

2221

1211

cc

HHHH

WWWW

CASE 2: a=0, c=c1, b=c2, d=0

(Permutation solution)

⎥⎦

⎤⎢⎣

⎡=⎥⎦⎤

⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡ccHH

HHWWWW

212221

1211

2221

1211 00CASE 3:

⎥⎦

⎤⎢⎣

⎡=⎥⎦

⎤⎢⎣

⎡⎥⎦

⎤⎢⎣

⎡00

21

2221

1211

2221

1211 ccHHHH

WWWWCASE 4: ( ) 0|| ≠fH

( ) 0≠fH ji

do not appearwe assumeQ

S1

S2

Y1

Y2

Same as ABF

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 23

Adaptive Beamformers0

C1S1

S2

S1

C2S2

BSS

Equivalence between BSS and ABFEquivalence between BSS and ABF

0

if the independent assumption ideally holdsBSS and ABF are equivalentif the independent assumption ideally holds

ST

ST

Physical Understanding of BSSPhysical Understanding of BSS

Directivity Patterns

TR = 300 ms TR = 0 ms

TR = 300 msTR = 0 ms

BSS

ABF

BSS, ABF ⇒ Spatial notch to jammer direction

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 24

BSS of Three SpeechesBSS of Three Speeches

3 sources3 sources××3 sensors BSS3 sensors BSS

Directivity Patterns

TR = 130 ms

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 25

3 sources3 sources××3 sensors BSS3 sensors BSS

Directivity Patterns

TR = 130 ms

3 sources3 sources××3 sensors BSS3 sensors BSS

Directivity Patterns

TR = 130 ms

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 26

4 cm

Spatial AliasingSpatial Aliasing

2λ<d

λ : wave length of the highest frequency

When microphone spacing d is too wide…

dd

Spatial aliasing does not occer when

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 27

4 cm30 cm

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 28

Rec

ogni

tion

rate

0%

20%

40%

60%

80%

100%

妨害音:新聞読み上げ 妨害音:DVD

ブラインド源分離前

ブラインド源分離後

After

Before

Before

After

Jammer : Speech Music + Speech

Effect on Speech RecognitionEffect on Speech Recognition

Permutation AlignmentVarious approaches and methodsMethods based on clustering

Bin-wise separated signalsaccording to their activities

Time difference of arrival (TDOA)estimated from basis vectors

Permutation ≈ ClusteringMembership assignment is restricted

to a permutation in each frequency bin

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 29

Dependence Across FrequenciesMeaningful audio source has some structure

Common silence period Common onset and offsetHarmonics

Mutual dependence of separated signals across frequencies

Permutation Alignment (Spatial Information)

Beamforming approach Directivity patterns calculated with Direction of arrival (DOA) estimated & clusteredArray geometry information needed

DOA

Time difference of arrival (TDOA)

Estimated from basis vectorsNo need for array information

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 30

• Mixtures

• ICA

• The inverse of separation matrix

• Decomposition of mixture

Basis VectorsBasis Vectors

basis vector

• Basis vector• represents the frequency responses

from source to all sensors• Implies information on the source location

Basis VectorsBasis Vectors

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 31

3-source 3-microphone Case

MicrophonesOn edges of 4cm triangle

Loudspeakers

45°

120°

210°Distance:

0.5, 1.1, 1.7 m

• Reverberation time: RT60 = 130, 200 ms

DOA: Definition and Example3-dim unit-norm vector

6 speakers and 8 microphones

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ICA2007 Keynote – Blind Audio Source Separation based on Independent Component AnalysisShoji Makino, Hiroshi Sawada, and Shoko Araki (NTT Communication Science Laboratories) 32

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ReferencesICA and BSS books

[Lee, 1998], [Haykin, 2000], [Hyvarinen et al., 2001], [Cichocki and Amari, 2002]

ICA algorithms

• Information-maximization approach [Bell and Sejnowski, 1995]• Maximum likelihood (ML) estimation [Cardoso, 1997]• Natural gradient [Amari et al., 1996], [Cichocki and Amari, 2002]• Equivariance property [Cardoso and Laheld, 1996]• FastICA [Hyvarinen et al., 2001]

Time-domain approach to convolutive BSS

[Amari et al., 1997], [Kawamoto et al., 1998], [Matsuoka and Nakashima, 2001],[Douglas and Sun, 2003], [Buchner et al., 2004], [Takatani et al., 2004], [Douglas et al., 2005],[Aichner et al., 2006]

Frequency-domain approach to convolutive BSS

[Smaragdis, 1998], [Parra and Spence, 2000], [Schobben and Sommen, 2002], [Murata et al., 2001],[Anemuller and Kollmeier, 2000], [Mitianoudis and Davies, 2003], [Asano et al., 2003],[Saruwatari et al., 2003], [Ikram and Morgan, 2005], [Sawada et al., 2004], [Mukai et al., 2006],[Sawada et al., 2006], [Hiroe, 2006], [Kim et al., 2007], [Lee et al., 2006], [Sawada et al., 2007]

Approaches to permutation alignment

• Making separation matrices smooth in the frequency domain [Smaragdis, 1998],[Parra and Spence, 2000], [Schobben and Sommen, 2002], [Buchner et al., 2004]

• Beamforming approach and estimating direction-of-arrival (DOA) [Saruwatari et al., 2003],[Ikram and Morgan, 2005], [Sawada et al., 2004], [Mukai et al., 2006], [Sawada et al., 2006]

• Correlation of envelopes [Murata et al., 2001], [Anemuller and Kollmeier, 2000],[Sawada et al., 2004]

• Nonstationary time-varying scale parameter [Mitianoudis and Davies, 2003]• Multivariate density function [Hiroe, 2006], [Kim et al., 2007], [Lee et al., 2006]• Dominance measure [Sawada et al., 2007]

Time-frequency masking approach to BSS

[Aoki et al., 2001], [Rickard et al., 2001], [Bofill, 2003], [Yilmaz and Rickard, 2004],[Roman et al., 2003], [Araki et al., 2004], [Araki et al., 2005], [Kolossa and Orglmeister, 2004],[Sawada et al., 2006]

Blind dereverberation for speech signals

[Nakatani et al., 2007], [Delcroix et al., 2007], [Kinoshita et al., 2006]

Scaling adjustment to microphone observations

[Cardoso, 1998], [Murata et al., 2001], [Matsuoka and Nakashima, 2001], [Takatani et al., 2004]

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Linear estimation

[Kailath et al., 2000]

Time difference of arrival (TDOA)

[Knapp and Carter, 1976], [Omologo and Svaizer, 1997], [DiBiase et al., 2001], [Chen et al., 2004]

K-means clustering

[Duda et al., 2000]

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