Sound Analysis and Noise Control

Preface.- Acknowledgments.- 1 Basics of Sound.- 1.1 Generation of Sound.- 1.2 Equations of Motion of Plane Waves.- 1.3 Velocity of Plane Waves.- 1.4 Specific Acoustic Impedance.- 1.5 Spherical Sound Waves.- 1.6 Sound Intensity.- 1.7 Levels.- 1.8 Waveform, Frequency, Pressure Change.- 1.9 The Decibel.- 1.10 Frequency Spectra of Sound.- References for Chapter 1.- 2 Mechanism of Hearing and Subjective Rating.- 2.1 Construction of the Ear.- 2.2 Functioning of the Mechanism.- 2.3 Subjective Response and Units for Rating of Noise.- 2.4 Loudness; Phons and Sones.- 2.5 Loudness of Short Duration Sounds.- 2.6 Age-Related Hearing Loss-Presbycusis.- 2.7 Noise-Induced Hearing Loss.- References for Chapter 2.- 3 Instrumentation for Noise Measurement.- 3.1 General.- 3.2 Microphones.- 3.3 Sound Level Meters.- 3.4 Weighting Curves.- 3.5 Basic Sound Level Meter System.- 3.6 Vibration Transducers.- 3.7 Frequency Analyzers and Filtering.- 3.8 Tape Recorders.- 3.9 Signal Processing.- 3.9.1 Leq Concept.- 3.9.2 The LN Concept.- 3.9.3 Level Recorders.- 3.9.4 Real-Time Analyzers (Digital and FFT).- 3.9.5 Sound Intensity Measurements.- References for Chapter 3.- 4 Sound Fields.- 4.1 Reflected Sound.- 4.2 Ideal Sound Source.- 4.3 Practical Sound Source.- 4.4 Anechoic Rooms.- 4.5 Reverberant Rooms.- 4.6 Directivity Index and Directivity Factor.- 4.7 Attenuation of Sound Pressure with Distance in a Free Field.- 4.8 Attenuation of Sound Pressure with Distance in an Enclosure.- 4.9 Propagation of Sound in Air.- 4.9.1 The Plane Source.- 4.9.2 The Point Source.- 4.9.3 The Line Source.- 4.9.4 General Factors Affecting Sound and Propagation.- 4.9.5 The Effects of Wind.- 4.9.6 The Effects of Temperature.- 4.9.7 Humidity and Precipitation.- 4.9.8 Absorption by Natural Features.- 4.9.9 Reflection.- 4.9.10 Absorption.- 4.9.11 Diffraction.- 4.10 Outdoor Barriers.- 4.10.1 Introduction.- 4.10.2 Path Length Difference.- 4.10.3 Thin Barriers.- 4.10.4 Thick Barriers.- 4.10.5 Fresnel Number.- 4.10.6 Attenuation for Point and Line Sources.- 4.10.7 Ground Attenuation.- 4.11 Attenuation Provided by Trees.- References for Chapter 4.- 5 Absorption, Silencers, Room Acoustics and Transmission Loss.- 5.1 Absorption.- 5.1.1 Introduction.- 5.1.2 Absorption Material.- 5.1.3 Panel Absorption.- 5.2 Dissipative, Reactive and Active Silencers.- 5.2.1 Dissipative Silencers.- 5.2.2 Reactive Silencers.- 5.2.3 Active Silencers.- 5.3 Behavior of Sound in Rooms.- 5.3.1 Reverberation and Decay of Sound in a Room.- 5.3.2 Calculation of Reverberation Time.- 5.3.3 Effect of Air Absorption on Decay Rate and Reverberation Time.- 5.3.4 Speech Intelligibility and Reverberation Time.- 5.3.5 Measurement of Random-Incidence Absorption Coefficient.- 5.3.6 Normal-Incidence Absorption Coefficient.- 5.4 Sound Transmission Loss and Sound Transmission Class.- 5.4.1 Transmission Loss.- 5.4.2 Sound Transmission Class STC.- 5.4.3 Transmission Loss of Composite Walls and Effect of Flanking.- References for Chapter 5.- 6 Vibration and Vibration Control.- 6.1 Introduction.- 6.2 Equation of Motion for a System Having a Single Degree of Freedom.- 6.3 Free Vibration without Damping.- 6.4 Free Vibration with Damping.- 6.5 Forced Vibrations without Damping.- 6.6 Transmissibility.- 6.7 Forced Vibration with Damping.- 6.8 Motion Disturbance-Single Degree of Freedom.- 6.9 Isolator Selection.- 6.10 Types of Isolators.- 6.11 A Mass Subjected to Motion in Several Degrees of Freedom-Coupled and Decoupled Modes.- 6.12 Vibration Criteria.- 6.13 Vibration Damping.- 6.13.1 General.- 6.13.2 Types of Treatments.- 6.13.3 Performance Characteristics.- 6.13.4 Frictional Damping.- 6.13.5 Common Damping Materials.- 6.13.6 Bonding.- 6.13.7 Laminates.- References for Chapter 6.- 7 Noise Criteria and Regulations.- 7.1 Introduction.- 7.2 Indices for Environmental Noise.- 7.2.1 Direct Rating.- 7.2.2 Perceived Noise Level.- 7.2.3 Equivalent Sound Level Leq.- 7.2.4 Day-Night Level Ldn.- 7.2.5 Exceedance Levels LN.- 7.2.6 Noise Pollution Level NPL.- 7.3 Criteria for Indoor Noise Environment.- 7.3.1 NC, PNC and RC Criteria.- 7.3.2 Direct Rating Guides and Standards.- 7.3.3 Speech Interference Level PSIL.- 7.3.4 Other Criteria (or Guides) for Indoor Environments.- 7.3.5 Speech Communication and Privacy.- 7.3.6 Open-Plan Offices.- 7.4 Regulations of Hearing-Damage Risk in Industry-the U.S. Occupational Safety and Health Act Standards.- 7.4.1 Background to OSHA Regulations.- 7.4.2 U.S. Occupational Safety and Health Act of 1970.- 7.4.3 Ear Protectors.- 7.4.4 Recent Studies in Canada Regarding Noise-Induced Hearing Loss and Damage Risk Criteria.- 7.5 Outdoor Noise Criteria.- 7.5.1 Typical Noise Levels, Statistical Community Noise, and Recommended Outdoor Limits.- 7.5.2 Rating Procedures.- 7.5.3 Psychoacoustic Studies on Aversiveness to Typical Noises.- References for Chapter 7.- 8 General Review of Noise Control and Practical Examples.- 8.1 General Review of Noise Control.- 8.1.1 General Noise Control Measures.- 8.1.2 A Program for Noise Control.- 8.1.3 Methods of Noise Reduction.- 8.1.4 Noise Measurement.- 8.2 Practical Examples of Noise Control Techniques.- 9 Noise Source Diagnosis and Case Studies.- 9.1 The Use of Sound Power Data in Source Diagnosis.- 9.2 Further Case Studies in Noise Control.- 9.2.1 Reduction of Noise Levels in a Food-Packaging Area.- 9.2.2 Reduction of Engine-Generator Cooling-Fan Noise.- 9.2.3 Reduction of Noise from a Mine Ventilation Fan.- 9.2.4 Reduction of Railcar Retarder Noise.- 9.2.5 Reduction of Mechanical Equipment Noise in a Penthouse Apartment.- 9.3 Case Study of Noise Reduction from a Centrifugal Pump and Motor Drive in a Laboratory.- 9.3.1 Introduction.- 9.3.2 The Problem.- 9.3.3 Suggested Procedure.- 9.3.4 Instrumentation.- 9.3.5 Comments on and Results of Typical Measurements.- 9.3.6 Sample Calculations.- 9.3.7 Results.- 9.3.8 Discussion.- 9.4 Example of Use of Silencer and Silencing Material in Ventilation System.- 9.5 NIOSH Case Histories.- 9.6 General Texts, Handbooks, and Manuals.- Credits for Figures and Tables.- Appendix I Glossary of Acoustical Terms.- Appendix II Conversion Factors.- Appendix III Acoustical Standards Organizations and Standard Documents.- Appendix IV Useful Acoustics Periodicals.- Appendix V Guidelines for Regulatory Control of Occupational Noise Exposure and Hearing Conservation.- Appendix VI Buyer's Guide to Products for Noise and Vibration Control.- Appendix VII Dynamic Measurement Instrumentation Buyer's Guide.