1. Microphone array
Raymond Sastraputera

2. Overview Introduction Implementation Experimentation Conclusion
Problem
Solution
Implementation
Experimentation
Conclusion

3. Introduction (Problem)
Signal coming to a microphone
Speech signal
Noise signal
Good signal consist of
High speech signal
Low noise signal

4. Introduction (Solution)
Microphone array
Beam forming theory
VAD
Cross correlation
Ref(1)

5. Implementation Matlab Data source Examine(file) Combine(file)
VAD(file)
Data source
Ref(2)

6. Samples in the Project Microphone array signal Position 1 2 3 4 5 6 78 …
Microphone Array
100 cm
7 cm
Microphone
Speaker 1 3 4 5 6 7 8 2

7. Beam forming Theory
delay travel distance
Microphone
Source

8. Microphone array output
Known source position
Easily combine
Unknown
Approximate the position
VAD
Combine

9. VAD Uses two size window Based on energy change Small Large
Small window > large window

10. VAD

11. Cross correlation
Obtaining delay in aligning several signals
Mid
max

12. Extra Solution Simulate the position of source
Std array of the signals
Lowest std = perfect alignment
Speaker y 1 2 3 4 5 6 7 8
Microphone Array
7 cm
Microphone

13. Result of Comparison Microphone array output .wav sound
Speech voice enhanced
Noise signal is reduced
Delay calculation
Actual
Approximation
cross correlation
extra solution 1
mid2m1
100 50 y
24.5 28

14. Conclusion and Summary
1. Microphone array enhance or amplify the speech signal (from a single source) and decrease the effect of the noise or other speech signal.
2. Beam forming theory works well if the distance between microphone is much smaller than the distance to the signal source. In this experiment, because the ration of the distance is not that much, the error rate is pretty high.

15. Reference
1. Weinstein, Eugene. “LOUD: A 1020-NODE MICROPHONE ARRAY AD ACOUSTIC BEAMFORMER”. Courant institute of Mathematical Science. Ed. Kenneth Steele. Tilera Corporation. Anant Agarwal, and James Glass. MIT Copmuter Science and Artificial Intelligence Laboratory.
2. Campbell, Davik K. “Adaptive Beamforming Using a Microphone Array for Hands-Free Telephony.” LOUD: A 1020-NODE MICROPHONE ARRAY AD ACOUSTIC BEAMFORMER”. February 16, Blacksburg, Virginia.
3. multi-microphone data recorded by Tom Sullivan at Carnegie Mellon University

16. Thank you
Any Questions?