background noise cancellation for acoustic detection of

205 Pages·2006·2.82 MB·English

BACKGROUND NOISE CANCELLATION FOR ACOUSTIC DETECTION OF
MANATEE VOCALIZATIONS

By

ZHENG YAN

A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA

2006
Copyright 2006

by

Zheng Yan
To my family
ACKNOWLEDGMENTS
The author would like to express his great gratitude to his advisors, Dr. Christopher
Niezrecki and Dr. Louis Cattafesta, for suggesting the topic of this work, providing
continuous guidance, support and encouragement throughout this research.
The author would like to thank Dr. Jose Principe for his guidance and advice from
the committee members, Dr. John Harris and Dr. Richard Lind. The author also would
like to thank his fellow students in the Smart Structures and Acoustic Laboratory and
Interdisciplinary Microsystems Group (IMG) for sharing their knowledge.
The author would like to express his sincere appreciation to the Florida Sea Grant,
Florida Fish and Wildlife Conservation Commission, and University of Florida Marine
Mammal Program in supporting this research.
Finally, the author gives special appreciation to my family, for their love, patience,
and support.

iv
TABLE OF CONTENTS
page
ACKNOWLEDGMENTS.................................................................................................iv
TABLE OF CONTENTS.....................................................................................................v
LIST OF TABLES...........................................................................................................viii
LIST OF FIGURES...........................................................................................................ix
NOMENCLATURE.......................................................................................................xvii
ABSTRACT.......................................................................................................................xx
CHAPTER
1 INTRODUCTION........................................................................................................1
Need for Manatee Detection System............................................................................1
Why Manatees Collide With Boats..............................................................................3
Contributions................................................................................................................5
Organization of the Dissertation...................................................................................7
2 RESEARCH BACKGROUND AND REVIEW OF DETECTION METHODS......11
Manatee Detection Methods.......................................................................................12
Acoustic Detection of Manatee Vocalizations...........................................................14
Vocalizations and Behavior of Manatees............................................................14
Major Background Noise....................................................................................18
Comparison Between Manatee Calls and Dolphin Calls....................................20
Other Methods of Acoustic Detection........................................................................21
Matched Filtering................................................................................................22
Hidden Markov Model (HMM)...........................................................................22
Artificial Neural Networks (ANN)......................................................................23
Spectrogram Correlation.....................................................................................23
3 REVIEW OF BACKGROUND NOISE CANCELLATION.....................................25
Adaptive Noise Cancellation (ANC)..........................................................................26
Feedforward ANC...............................................................................................26
Feedback ANC....................................................................................................27
v
ANC for Underwater Acoustics..........................................................................27
ANC without Reference Input.............................................................................29
ANC Structures...................................................................................................30
Blind Signal Separation (BSS)...................................................................................31
Wavelet-Based Noise Reduction................................................................................34
Conclusions.................................................................................................................36
4 ADAPTIVE LINE ENHANCER (ALE)....................................................................37
General Adaptive Filter..............................................................................................37
Wiener Filter........................................................................................................38
Least Mean Square (LMS)..................................................................................40
Limitations of the LMS Algorithm and ANC System.........................................41
Theory of FIR-ALE....................................................................................................44
Theory of IIR-ALE.....................................................................................................46
Review of ALE...........................................................................................................48
FIR Structure ALE..............................................................................................48
IIR Structure ALE...............................................................................................50
Feedback Adaptive Line Enhancer (FALE)...............................................................52
5 ESTABLISHMENT OF THE MANATEE LIBRARY.............................................55
6 SIMULATION RESULTS AND ANALYSES..........................................................59
Signal Preprocessing...................................................................................................59
Parameter Selection of ALE.......................................................................................60
Review of Delay Parameter.................................................................................60
Delay Parameter for Manatee Problem...............................................................63
Review of Optimal Order and Step Size.............................................................66
Order for Manatee Problem.................................................................................67
Variable Step Size ALE.......................................................................................70
Feedback Constant...............................................................................................71
Simulation Results in Time Domain...........................................................................72
Simulation Results in Terms of SNR..........................................................................77
Results on Acoustic Superposition of Manatee Vocalizations...................................90
Field Test....................................................................................................................92
Description of Field Test.....................................................................................92
Conversion From Spherical to Mixed Spreading................................................94
Simulation Results...............................................................................................95
7 PERFORMANCE COMPARISON BETWEEN FIR-ALE AND FALE................103
Computational Complexity.......................................................................................103
FIR-ALE............................................................................................................103
FALE.................................................................................................................104
Stability.....................................................................................................................106
Convergence Rate and Tracking Ability..................................................................107
vi
Advantage and Disadvantage of FIR-ALE and FALE.............................................110
8 DETECTION RANGE ESTIMATION....................................................................113
Theoretical Development..........................................................................................113
Estimation of Improved Detection Range................................................................115
Estimation of the Improved Detection Range..........................................................122
SPL of Manatee Vocalizations and Background Noise....................................122
Estimation of Detection Range (bandpass filter)...............................................123
Estimation of Detection Range (FIR-ALE).......................................................125
Estimation of Detection Range (FALE)............................................................125
9 REAL TIME SIMULATION...................................................................................133
Experimental Laboratory Setup................................................................................134
Simulink Block Diagrams and Implementation.......................................................134
dSPACE Layout........................................................................................................139
Simulation Results....................................................................................................141
10 CONCLUSIONS AND FUTURE WORK...............................................................146
Conclusions...............................................................................................................146
Future Work..............................................................................................................147
APPENDIX
A OPTIMAL DELAY PARAMETER OF ALE..........................................................150
Evaluation Criterion..................................................................................................151
One Sinusoid Corrupted by White Noise.................................................................153
Two Sinusoids Corrupted by White Noise...............................................................155
Three Sinusoids Corrupted by White Noise.............................................................156
Common Characteristics for These Three Cases......................................................157
Proposed Performance Evaluation Criterion............................................................160
Conclusions...............................................................................................................162
B MANATEE VOCALIZATIONS IN THE LIBRARY.............................................163
LIST OF REFERENCES.................................................................................................174
BIOGRAPHICAL SKETCH...........................................................................................184

vii
LIST OF TABLES
Table page

6-1. Parameters of ALE (FIR-ALE and FALE) for the simulations..................................72
6-2. The average performance of bandpass filter, FIR-ALE and FALE for the manatee
calls corresponding to each category (dB)...............................................................83
7-1. Computational complexity of FIR-ALE...................................................................104
7-2. Computational complexity of FALE........................................................................105
9-1. Description of tracks used for testing.......................................................................142
9-2. Detection results of the system without noise reduction for each track...................143
9-3. Detection results of the system with noise reduction for each track........................144
9-4. Results of the comparison between the system without and with noise reduction...145

viii
LIST OF FIGURES
Figure page

1-1. Manatee surfacing for air..............................................................................................2
1-2. Number of manatee deaths from watercraft collisions from 1976 to 2001 and
percentage breakdown of total manatee deaths..........................................................2
1-3. Alert sign and boater in manatee zone..........................................................................3
2-1. Conceptual sketch of manatee warning system..........................................................15
2-2. Frequency spectrum of a typical manatee vocalization..............................................17
2-3. Spectrogram of typical manatee vocalizations...........................................................17
2-4. Typical snapping shrimp noise in time domain..........................................................19
2-5. Frequency spectrum of typical boat noise..................................................................20
2-6. Frequency spectrum of natural noise..........................................................................20
2-7. Spectrogram of three typical dolphin whistles...........................................................21
3-1. Broadband feedforward ANC system.........................................................................26
3-2. Illustration of blind signal separation.........................................................................32
3-3. Herault-Jutten method for blind signal separation.....................................................33
4-1. Block diagram of Wiener filter...................................................................................39
4-2. Simplified block diagram of adaptive noise canceller based on LMS algorithm.......41
4-3. Block diagram of an ANC system under realistic conditions....................................43
4-4. Block diagram of FIR-ALE........................................................................................44
4-5. Block diagram of IIR-ALE.........................................................................................47
4-6. The relationship between the SNR of input and the gain of ALE..............................49
ix
4-7. Block Diagram of Feedback Adaptive Line Enhancer (FALE).................................53
5-1. The procedure of classifying manatee calls................................................................57
6-1. Autocorrelation of manatee vocalizations and background noise. (a) pure manatee
vocalization, (b) natural noise and (c) boat noise.....................................................66
6-2. Power spectrum of a typical manatee vocalization (from category 1110).................68
6-3. The instantaneous transfer function of FIR-ALE during the manatee call period
when the order of adaptive filter is set to 70............................................................68
6-4. The instantaneous transfer function of FIR-ALE during the manatee call period
when the order of adaptive filter is set to 20............................................................69
6-5. The instantaneous transfer function of FIR-ALE outside the period of the manatee
call when the order of adaptive filter is set to 20.....................................................70
6-6. Manatee vocalizations and background noise in time domain. (a) pure manatee
vocalizations, (b) natural noise, (c) boat dominated noise, (d) snapping shrimp
noise and (e) superposition of manatee calls, natural noise, boat dominated
noise, and snapping shrimp noise.............................................................................73
6-7. Performance of bandpass filter, FIR-ALE, and FALE in time domain. (a) after the
band pass filter is applied, (b) after FIR-ALE is applied and (c) after FALE is
applied......................................................................................................................74
6-8. Spectrogram of the five original manatee calls..........................................................75
6-9. Spectrogram of the manatee calls after band pass filter is applied.............................76
6-10. Spectrogram of the manatee calls after FIR-ALE is applied....................................76
6-11. Spectrogram of the manatee calls after FALE is applied.........................................76
6-12. The method used to compute the SNR of an original manatee call. (a) pure
manatee call and (b) background noise....................................................................78
6-13. The method used to compute the SNR of the manatee call after filtering. (a)
superposed signal of pure manatee call and background noise after FALE is
applied and (b) background noise after FALE is applied.........................................78
6-14. SNR of each manatee vocalization after band pass filter is applied when SNR
ori
is equal to -5 dB.......................................................................................................79
6-15. SNR of each manatee vocalization after FIR-ALE is applied when SNR is
ori
equal to -5 dB...........................................................................................................80
x