Contents
Blind Decomposition of Binaural Mixed
Signals Using Multistage SIMO-ICA

Introduction
Research Goal
Mixing Process
Single-Input Multiple-Output model

Tomoya TAKATANI, Satoshi Ukai
Hiroshi SARUWATARI, Kiyohiro SHIKANO
Speech and Acoustics Processing Laboratory
Graduate School of Information Science
Nara Institute of Science and Technology

Conventional Decomposition method
Proposed Decomposition Method
Experiments
Conditions
Results

Conclusion

Introduction(Binaural Sound Reproduction System)
Head and Torso
Simulator(HATS)

Research Goal
FemaleandFemaleisisleft
centermaleis isright.
andmaleright.

Female is left
and male is rightSystemSystem
Primary fieldPrimary field

Binaural sound reproduction system can copy the primary sound field.
⇒ However, This system can not enhance and modify the target
audio signals.

Realization of audio augmented reality system which canenhance and modify the target audio signals

Application

Mixing process (1/2)
Source1

Telepresence (Telexistance) system using visualmodality and audio modality

Robot

Secondary field

Secondary field

Operator (User)

Source2

Source 1

Right ear

Source 2

Left ear•1Mixing process (2/2)

Approach

A11(z )s1 (t )s1 (t )s1 (t )
A21(z )s1 (t )A11(z )s1 (t )A12 (z )s2 (t )s1 (t )SIMO model 1s2 (t )

A11( z )s1 (t )s1 (t )

A21(z )s1 (t )A12 (z )s2 (t )s2 (t )A22 (z )s2 (t )A21(z )s1 (t )A22 (z )s2 (t )BlindDecomposing
Process

A21(z )s1 (t )SIMO model 1
A12 (z )s2 (t )A12 (z )s2 (t )Mixed signals (primary field)s2 (t )A22 (z )s2 (t )Primary field

A21 (z )s1 (t ) + A22 (z )s2 (t )Left earThe mixed signals are sum of the SIMO-model-based signals.

A11 (z )s1 (t )+signals without a priori information.

A12 (z )s2 (t )Proposed Multistage SIMO-ICA (MS-SIMO-ICA)(ICASSP2004, Ukai, Takatani et al.)A11 (z )s1 (t )A21 (z )s1 (t )+y1ICA (t )A22 (z )s2 (t )ICAs2 (t )

FidelityController

y2ICA (t )A12 (z )s2 (t )A21 (z )s1 (t )y2FC (t )A21 (z )s1 (t − D / 2)

FDICA

A21 (z )s1 (t − D / 2)

SIMO-ICAFDICA and projection back generate the valid initialvalue of the separation filter of SIMO-ICA.

Proposed method: MS-SIMO-ICA

Experimental conditions
4.25 m

0.58 m0.74 mzLoudspeakers(Height:1.17 m)
s1 (t )

1.50 mMicrophones(Height:1.17 m)

Reverberation
Time: 200 ms

s 2 (t )θ1 θ2

4.25 m

A12 (z )s2 (t − D / 2)

Projection Back

Blind decomposition experiments ofbinaural mixed signals
In order to evaluate its effectiveness, decomposition
experiments of binaural mixed signals are carried out forthe different directions of sources.

A22 (z )s2 (t − D / 2)s2 (t )

2.04 m
2.02 mProblem of SIMO-ICA
The performance of SIMO-ICA depends on the initialvalue of the separation filter.

 Conventional method： SIMO-ICA

A11 (z )s1 (t − D / 2)

A22 (z )s2 (t )SIMO-ICAzMS-SIMO-ICA+

A22 (z )s2 (t − D / 2)
A12 (z )s2 (t − D / 2)y+s1 (t )A11 (z )s1 (t − D / 2)

(t )

FC1

A22 (z )s2 (t )SIMO model 2
we have to decompose the mixed signals into the SIMO-model-based

SIMO-Model-Based ICA (SIMO-ICA)(IWAENC2003, Takatani et al.)s1 (t )s2 (t )

Right ear A11 (z )s1 (t ) + A12 (z )s2 (t )SIMO model 2A11(z )s1 (t )HATSSound source

2 male and 2 female(12 combination)

Sampling
frequency

8000 Hz

Length of filter

1024 [taps]

Initial value offilter

Inverse filter of HRTF
whose directions ofsources are ±60 [deg]Step size
parameter α

1.0×10-6 [taps]

Evaluation
score

SIMO-model Accuracy
[dB]

•2

Evaluation Score: SIMO-Model Accuracy (SA)Experimental results

Similarity between the output signals of the ICA and real
SIMO-model-based signals
A11 (z )s1 (t )+A12 (z )s2 (t )A21 (z )s1 (t )+A22 (z )s2 (t )Output 1

Blind
Decomposing
ProcessOutput 2
Output 3
Output 4

SA = 10log10

Real SIMO - model - based signal

2t

Real SIMO - model - based signal − Output signal

2t

The performance of the outputs in the proposed
method is superior to that in conventional method.

Conclusion
We propose a new blind decomposition using
multistage single-input multiple-output (SIMO)model-based ICA for audio augmented realitysystem.
 The proposed method can blindly generate thevalid initial value of the separation filter in SIMOICA.
 The experimental results reveal that theperformance of the outputs in the proposed method
is superior to that in conventional method.
•3