Industrial Noise Control and Acoustics – Randall F. Barron

I.Industrial Noise Control and Acoustics

Industrial Noise Control and Acoustics – Randall F. Barron có 543 trang

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Industrial Noise Control and Acoustics
Industrial Noise Control and Acoustics – Randall F. Barron

II. MỤC LỤC

Preface iii

1 Introduction 1

1.1 Noise Control 1

1.2 Historical Background 3

1.3 Principles of Noise Control 7

1.3.1 Noise Control at the Source 8

1.3.2 Noise Control in the Transmission Path 9

1.3.3 Noise Control at the Receiver 9

References 10

2 Basics of Acoustics 12

2.1 Speed of Sound 12

2.2 Wavelength, Frequency, and Wave Number 13

2.3 Acoustic Pressure and Particle Velocity 15

2.4 Acoustic Intensity and Acoustic Energy Density 17

2.5 Spherical Waves 21

2.6 Directivity Factor and Directivity Index 24

2.7 Levels and the Decibel 27

2.8 Combination of Sound Sources 31

Copyright © 2003 Marcel Dekker, Inc.

2.9 Octave Bands 33

2.10 Weighted Sound Levels 34

Problems 37

References 40

3 Acoustic Measurements 41

3.1 Sound Level Meters 42

3.2 Intensity Level Meters 46

3.3 Octave Band Filters 49

3.4 Acoustic Analyzers 50

3.5 Dosimeter 50

3.6 Measurement of Sound Power 51

3.6.1 Sound Power Measurement in a Reverberant

Room 52

3.6.2 Sound Power Measurement in an Anechoic or

Semi-Anechoic Room 58

3.6.3 Sound Power Survey Measurements 62

3.6.4 Measurement of the Directivity Factor 66

3.7 Noise Measurement Procedures 69

Problems 73

References 76

4 Transmission of Sound 78

4.1 The Wave Equation 78

4.2 Complex Number Notation 83

4.3 Wave Equation Solution 84

4.4 Solution for Spherical Waves 88

4.5 Changes in Media with Normal Incidence 91

4.6 Changes in Media with Oblique Incidence 96

4.7 Sound Transmission Through a Wall 101

4.8 Transmission Loss for Walls 107

4.8.1 Region I: Stiffness-Controlled Region 108

4.8.2 Resonant Frequency 111

4.8.3 Region II: Mass-Controlled Region 112

4.8.4 Critical Frequency 113

4.8.5 Region III: Damping-Controlled Region 113

4.9 Approximate Method for Estimating the TL 117

4.10 Transmission Loss for Composite Walls 120

4.10.1 Elements in Parallel 121

4.10.2 Composite Wall with Air Space 122

4.10.3 Two-Layer Laminate 127

4.10.4 Rib-Stiffened Panels 131

Copyright © 2003 Marcel Dekker, Inc.

4.11 Sound Transmission Class 134

4.12 Absorption of Sound 139

4.13 Attenuation Coefficient 143

Problems 153

References 160

5 Noise Sources 162

5.1 Sound Transmission Indoors and Outdoors 162

5.2 Fan Noise 164

5.3 Electric Motor Noise 169

5.4 Pump Noise 171

5.5 Gas Compressor Noise 173

5.6 Transformer Noise 177

5.7 Cooling Tower Noise 178

5.8 Noise from Gas Vents 182

5.9 Appliance and Equipment Noise 185

5.10 Valve Noise 186

5.11 Air Distribution System Noise 192

5.10.1 Sources of Valve Noise 186

5.10.2 Noise Prediction for Gas Flows 188

5.10.3 Noise Prediction for Liquid Flows 190

5.11.1 Noise Attenuation in Air Distribution

Systems 193

5.11.2 Noise Generation in Air Distribution System

Fittings 195

5.11.3 Noise Generation in Grilles 198

5.12 Traffic Noise 207

5.13 Train Noise 211

5.13.1 Railroad Car Noise 211

5.13.2 Locomotive Noise 213

5.13.3 Complete Train Noise 214

Industrial noiseProblems 217

Industrial noise references 222

6 Acoustic Criteria 225

6.1 The Human Ear 226

6.2 Hearing Loss 229

6.3 Industrial Noise Criteria 231

6.4 Speech Interference Level 235

6.5 Noise Criteria for Interior Spaces 238

6.6 Community Reaction to Environmental Noise 243

6.7 The Day-Night Level 247

Copyright © 2003 Marcel Dekker, Inc.

6.8 HUD Criteria 253

6.9 Aircraft Noise Criteria 255

6.7.1 EPA Criteria 247

6.7.2 Estimation of Community Reaction 250

6.9.1 Perceived Noise Level 256

6.9.2 Noise Exposure Forecast 257

Problems 262

References 267

7 Room Acoustics 269

7.1 Surface Absorption Coefficients 269

7.1.1 Values for Surface Absorption Coefficients 269

7.1.2 Noise Reduction Coefficient 270

7.1.3 Mechanism of Acoustic Absorption 271

7.1.4 Average Absorption Coefficient 274

7.2 Steady-State Sound Level in a Room 274

7.3 Reverberation Time 281

7.4 Effect of Energy Absorption in the Air 289

7.5 Noise from an Adjacent Room 293

7.6 Acoustic Enclosures 299

7.7 Acoustic Barriers 312

7.4.1 Steady-State Sound Level with Absorption in

the Air 289

7.4.2 Reverberation Time with Absorption in the

Air 291

7.5.1 Sound Source Covering One Wall 293

7.5.2 Sound Transmission from an Adjacent Room 295

7.6.1 Small Acoustic Enclosures 300

7.6.2 Large Acoustic Enclosures 304

7.6.3 Design Practice for Enclosures 311

7.7.1 Barriers Located Outdoors 313

7.7.2 Barriers Located Indoors 317

Problems 321

References 328

8 Silencer Design 330

8.1 Silencer Design Requirements 330

8.2 Lumped Parameter Analysis 332

8.2.1 Acoustic Mass 332

8.2.2 Acoustic Compliance 335

8.2.3 Acoustic Resistance 338

8.2.4 Transfer Matrix 339

Copyright © 2003 Marcel Dekker, Inc.

8.3 The Helmholtz Resonator 341

8.4 Side Branch Mufflers 350

8.5 Expansion Chamber Mufflers 368

8.6 Dissipative Mufflers 377

8.7 Evaluation of the Attenuation Coefficient 381

8.3.1 Helmholtz Resonator System 341

8.3.2 Resonance for the Helmholtz Resonator 342

8.3.3 Acoustic Impedance for the Helmholtz

Resonator 343

8.3.4 Half-Power Bandwidth 344

8.3.5 Sound Pressure Level Gain 348

8.4.1 Transmission Loss for a Side-Branch Muffler 351

8.4.2 Directed Design Procedure for Side-Branch

Mufflers 357

8.4.3 Closed Tube as a Side-Branch Muffler 361

8.4.4 Open Tube (Orifice) as a Side Branch 365

8.5.1 Transmission Loss for an Expansion Chamber

Muffler 368

8.5.2 Design Procedure for Single-Expansion

Chamber Mufflers 371

8.5.3 Double-Chamber Mufflers 373

8.7.1 Estimation of the Attenuation Coefficient 381

8.7.2 Effective Density 383

8.7.3 Effective Elasticity Coefficient 384

8.7.4 Effective Specific Flow Resistance 385

8.7.5 Correction for Random Incidence End Effects 387

8.8 Commercial Silencers 389

8.9 Plenum Chambers 391

Problems 397

References 405

9 Vibration Isolation for Noise Control 406

9.1 Undamped Single-Degree-of-Freedom (SDOF) System 407

9.2 Damped Single-Degree-of-Freedom (SDOF) System 410

9.2.1 Critically Damped System 411

9.2.2 Over-Damped System 412

9.2.3 Under-Damped System 412

9.3 Damping Factors 413

9.4 Forced Vibration 419

9.5 Mechanical Impedance and Mobility 424

9.6 Transmissibility 427

9.7 Rotating Unbalance 431

Copyright © 2003 Marcel Dekker, Inc.

9.8 Displacement Excitation 436

9.9 Dynamic Vibration Isolator 439

9.10 Vibration Isolation Materials 446

9.11 Effects of Vibration on Humans 464

Problems 469

9.10.1 Cork and Felt Resilient Materials 446

9.10.2 Rubber and Elastomer Vibration Isolators 450

9.10.3 Metal Spring Isolators 457

References 474

10 Case Studies in Noise Control 475

10.1 Introduction 475

10.2 Folding Carton Packing Station Noise 476

10.3 Metal Cut-Off Saw Noise 480

10.4 Paper Machine Wet End 482

10.5 Air Scrap Handling Duct Noise 488

10.2.1 Analysis 476

10.2.2 Control Approach Chosen 479

10.2.3 Cost 479

10.2.4 Pitfalls 480

10.3.1 Analysis 480

10.3.2 Control Approach Chosen 481

10.3.3 Cost 482

10.3.4 Pitfalls 482

10.4.1 Analysis 483

10.4.2 Control Approach Chosen 487

10.4.3 Cost 487

10.4.4 Pitfalls 488

10.5.1 Analysis 488

10.5.2 Control Approach Chosen 491

10.5.3 Cost 492

10.5.4 Pitfalls 492

10.6 Air-Operated Hoist Motor 492

10.7 Blanking Press Noise 494

10.8 Noise in a Small Meeting Room 498

10.7.1 Analysis 495

10.7.2 Control Approach Chosen 497

10.7.3 Cost 497

10.7.4 Pitfalls 497

10.8.1 Analysis 499

10.8.2 Control Approach Chosen 502

10.8.3 Cost 503

Copyright © 2003 Marcel Dekker, Inc.

10.8.4 Pitfalls 503

Problems 503

References 504

Appendix A Preferred Prefixes in SI 506

Appendix B Properties of Gases, Liquids, and Solids 507

Appendix C Plate Properties of Solids 509

Appendix D Surface Absorption Coefficients 510

Appendix E Industrial noise and industrial noise 511

Appendix F Nomenclature 514

Industrial Noise Control and Acoustics – Randall F. Barron
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