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Estimation of Sound Source Direction Using Parabolic Reflection Board. 2008 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP’08) 6-8 March, 2008 Watermark Hotel, Australia. Tetsuya Takiguchi, Ryoichi Takashima and Yasuo Ariki Kobe University, Japan.
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2008 RISP International Workshop on Nonlinear Circuits and Signal Processing (NCSP’08)
6-8 March, 2008 Watermark Hotel, Australia
Tetsuya Takiguchi, Ryoichi Takashima and Yasuo Ariki
Kobe University, Japan
If the system direction of the target signal source, …
Noise disturb the speech recognition
Search robot for disaster victims
Estimation of speaker for the meeting system
Sound-source-direction estimation technique is necessary for various systems
A is talking now.
Two or more microphones are necessary for conventional method
It is difficult to estimateof the signal arrival using only a single microphone
Goal: Sound-source-direction estimation
using only a single microphone
Any wave, where the sound source is located directly in front of the parabolic surface, is reflected toward the focal point.
No reflection waves, where the sound source is not located directly in front of the parabolic surface,will travel toward the focal point.
The signal is coming from directly infront of the parabolic surface
s1 : Direct sound
s2: Reflection sound
Distance difference between path s1 and s2 to the focal point:
QP+PO = QP+PH = 2d
d : distance of the focal point
Time difference to the focal point:
a: sound speed
(depending only on ‘d’)
Time difference for all reflection paths is equal to 2d/a.
The signal is coming from directly in front of the parabolic surface
The use of parabolic reflector can increase the power gain of the signal
arriving from the front of the parabolic reflector according to
The sound source is not located directly in front of the parabolic surface.
O: Focal point
No reflection waves will travel toward the focal point!
A microphone is set up at the focal point.
The microphone rotates and the power of the target signal observed at each angle is calculated.
The direction having maximum power is selected as the sound source direction.
i : angle of the parabolic reflector
Target source: 90 degrees
Source signal: white noise
The angle of the microphone with the parabolic reflector is changed manually from 0 degrees to 180 degrees at an interval of 10 degrees.
(The directivity of the microphone is set up opposite the sound source)
diffraction of the sound wave
Angle of mic.
Effect is not so great for the low-frequency components of the signal.
Power spectrum becomes larger as the angle of parabolic reflector is closer to 90 degrees.
The shape of the spectrum is not flat.
A sound-source-direction estimation method using a single microphone only.
New Proposed Method :
Active microphone with parabolic reflection board is able to estimate the sound source direction using only a single microphone.
In future work :
research for short signal (for example, speech)
form of the parabolic reflector