Sound Analysis and Noise Control

ISBN-13: 9781468466799 / Angielski / Miękka / 2012 / 461 str.

John Foreman

Opis

This book has been written to provide an intro Chapter 2 deals with the mechanism of hear duction to the fundamental concepts of sound ing and the subjective rating of sound, includ and a comprehensive coverage whereby un ing age-related and noise-induced hearing loss. wanted sound (noise) can be controlled. Al Assessment of any noise problem involves a though there are many notable textbooks which knowledge of the instrumentation available for deal primarily with the physics (or theory) of measurements, the limitations of this instru sound, and others which treat noise control in mentation, the appropriate procedures for mak a strictly practical (and sometimes even empir ing the measurements with the instrumentation, ical) manner, there are few textbooks that pro and the methods by which the measured data vide a bridging between the necessary under can be analyzed. Chapter 3 provides an up-to standing of the fundamentals of sound (its date coverage of these requirements, including generation, propagation, measurement) and the a section on one of the newest and most valu application of these fundamentals to its control. able tools in noise studies-sound intensity This book provides that link. measurement. The capability of being able to The text presents noise control primarily at measure sound intensity as compared with con the introductory level."

Spis treści

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.