NCHRP Report 635: Acoustic Beamforming: Mapping Sources of Truck Noise

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Table of Contents
Front Matter R1-R9
Summary 1-5
1.2 Heavy Truck Noise Sources 6-6
1.3 Source Identification Methods 7-8
1.4 Objective and Scope of Research 9-9
Task 5. Execute Testing Plan 10-10
Task 9. Submit Final Report 11-11
3.2.1 Noise Mapping Technique Development 12-12
3.2.2 Microphone Array Design 13-13
3.2.3 Balance Between Array Aperture and Spherical Spreading Loss 14-16
3.2.4 Design Conclusions 17-18
3.3.3 Preliminary Testing 19-19
3.4.1 Low-Speed Tests 20-21
3.4.2 High-Speed Tests 22-22
3.4.3 Passby and Intensity Measurements 23-30
3.5.1 Beamformer Calibrations with Spherical Source 31-33
3.5.2 Benchmark Measurements of Spherical Source on Moving Truck with Competing Truck Noise 34-34
3.5.3 Benchmark Parallel Array-Based and Acoustic Intensity Measurements for Stationary Trucks 35-40
3.5.4.1 Analysis Technique for Low- and High-Speed Track Passbys 41-43
3.5.4.2 Passby Evaluations of the 5900i Truck: Localization of Engine Compartment and Tire Noise 44-45
3.5.4.3 Passby Evaluations of the 9200i Truck: Localization of Engine Compartment and Exhaust Noise 46-47
3.5.4.4 Evaluations of the Truck Acoustic Source Level During Passby as a Function of Vertical Elevation 48-52
3.6.2 Data Post-Processing Algorithm Modifications 53-53
3.6.4 Roadside Measurement Setup 54-54
3.7.2 Image Results of the Vehicle Passbys 55-67
3.7.3 Example Model of Truck Sources for Simulating Noise Propagation Results of the Vehicle Passbys 68-70
4.2 Recommendations 71-72
References 73-74
Appendix A - Array Microphone Coordinates 75-75
Appendix B - Vertical Distributions of Noise Sources for Heavy Trucks 76-77
Appendix C - Glossary of Special Terms 78-79
Abbreviations used without definitions in TRB publications 80-80

Table of Contents

Front Matter R1-R9

Summary 1-5

1.2 Heavy Truck Noise Sources 6-6

1.3 Source Identification Methods 7-8

1.4 Objective and Scope of Research 9-9

Task 5. Execute Testing Plan 10-10

Task 9. Submit Final Report 11-11

3.2.1 Noise Mapping Technique Development 12-12

3.2.2 Microphone Array Design 13-13

3.2.3 Balance Between Array Aperture and Spherical Spreading Loss 14-16

3.2.4 Design Conclusions 17-18

3.3.3 Preliminary Testing 19-19

3.4.1 Low-Speed Tests 20-21

3.4.2 High-Speed Tests 22-22

3.4.3 Passby and Intensity Measurements 23-30

3.5.1 Beamformer Calibrations with Spherical Source 31-33

3.5.2 Benchmark Measurements of Spherical Source on Moving Truck with Competing Truck Noise 34-34

3.5.3 Benchmark Parallel Array-Based and Acoustic Intensity Measurements for Stationary Trucks 35-40

3.5.4.1 Analysis Technique for Low- and High-Speed Track Passbys 41-43

3.5.4.2 Passby Evaluations of the 5900i Truck: Localization of Engine Compartment and Tire Noise 44-45

3.5.4.3 Passby Evaluations of the 9200i Truck: Localization of Engine Compartment and Exhaust Noise 46-47

3.5.4.4 Evaluations of the Truck Acoustic Source Level During Passby as a Function of Vertical Elevation 48-52

3.6.2 Data Post-Processing Algorithm Modifications 53-53

3.6.4 Roadside Measurement Setup 54-54

3.7.2 Image Results of the Vehicle Passbys 55-67

3.7.3 Example Model of Truck Sources for Simulating Noise Propagation Results of the Vehicle Passbys 68-70

4.2 Recommendations 71-72

References 73-74

Appendix A - Array Microphone Coordinates 75-75

Appendix B - Vertical Distributions of Noise Sources for Heavy Trucks 76-77

Appendix C - Glossary of Special Terms 78-79

Abbreviations used without definitions in TRB publications 80-80