Engineering Noise Control

Cover
Half Title
Title Page
Copyright Page
Dedication
Contents
Preface to the First Edition
Preface to the Fourth Edition
Preface to the Fifth Edition
Preface to the Sixth Edition
Acknowledgements
1. Fundamentals and Basic Terminology
1.1. Introduction
1.2. Noise-Control Strategies
1.2.1. Sound Source Modification
1.2.2. Control of the Transmission Path
1.2.3. Modification of the Receiver
1.2.4. Existing Facilities
1.2.5. Facilities in the Design Stage
1.2.6. Airborne versus Structure-Borne Noise
1.3. Acoustical Standards and Software
1.4. Acoustic Field Variables
1.4.1. Variables
1.4.2. Acoustic Field
1.4.3. Magnitudes
1.4.4. Speed of Sound
1.4.5. Dispersion
1.4.6. Acoustic Potential Function
1.4.7. Wave Equation
1.4.8. Complex Number Formulations
1.5. Plane, Cylindrical and Spherical Waves
1.5.1. Plane Wave Propagation
1.5.2. Cylindrical Wave Propagation
1.5.3. Spherical Wave Propagation
1.5.4. Wave Summation
1.5.5. Plane Standing Waves
1.5.6. Spherical Standing Waves
1.6. Mean Square Quantities
1.7. Energy Density
1.8. Sound Intensity
1.8.1. Definitions
1.8.2. Plane Wave and Far-Field Intensity
1.8.3. Spherical Wave Intensity
1.9. Sound Power
1.10. Decibels
1.11. Combining Sound Pressures
1.11.1. Coherent and Incoherent Sounds
1.11.2. Addition of Coherent Sound Pressures
1.11.3. Addition of Incoherent Sounds (Logarithmic Addition)
1.11.4. Logarithmic versus Arithmetic Addition and Averaging
1.11.5. Subtraction of Sound Pressure Levels
1.11.6. Combining Level Reductions
1.12. Beating
1.13. Amplitude Modulation and Amplitude Variation
1.14. Basic Frequency Analysis
1.14.1. Frequency Bands
1.15. Doppler Shift
1.16. Impedance
1.16.1. Mechanical Impedance, ZM
1.16.2. Specific Acoustic Impedance, Zs
1.16.3. Acoustic Impedance, ZA
1.17. Flow Resistance
2. Human Hearing and Noise Criteria
2.1. Brief Description of the Ear
2.1.1. External Ear
2.1.2. Middle Ear
2.1.3. Inner Ear
2.1.4. Cochlear Duct or Partition
2.1.5. Hair Cells
2.1.6. Neural Encoding
2.1.7. Linear Array of Uncoupled Oscillators
2.1.8. Mechanical Properties of the Central Partition
2.1.8.1. Basilar Membrane Travelling Wave
2.1.8.2. Energy Transport and Group Speed
2.1.8.3. Undamping
2.1.8.4. The Half-Octave Shift
2.1.8.5. Frequency Response
2.1.8.6. Critical Frequency Band
2.1.8.7. Frequency Resolution
2.2. Subjective Response to Sound Pressure Level
2.2.1. Masking
2.2.2. Loudness
2.2.3. Comparative Loudness and the Phon
2.2.4. Low-Frequency Loudness
2.2.5. Relative Loudness and the Sone
2.2.6. Pitch
2.3. Weighting Networks
2.4. Noise Measures
2.4.1. Equivalent Continuous Sound Pressure Level, Leq
2.4.2. A-Weighted Equivalent Continuous Sound Pressure Level, LAeq
2.4.3. Noise Exposure Level, LEX,8h or LEX or Lep'd
2.4.4. A-Weighted Sound Exposure, EA,T
2.4.5. A-Weighted Sound Exposure Level, LAE or SEL
2.4.6. Day-Night Average Sound Pressure Level, Ldn or DNL
2.4.7. Community Noise Equivalent Level, Lden or CNEL
2.4.8. Effective Perceived Noise Level, LEPN or EPNL
2.4.9. Statistical Descriptors
2.4.10. Other Descriptors, Lmax, Lpeak, LImp
2.5. Hearing Loss
2.5.1. Threshold Shift
2.5.2. Presbyacusis
2.5.3. Noise-Induced Hearing Loss
2.6. Hearing Damage Risk
2.6.1. Requirements for Speech Recognition
2.6.2. Quantifying Hearing Damage Risk
2.6.3. International Standards Organisation Formulation
2.6.4. United States Standard Formulation
2.6.5. Alternative Formulations
2.6.5.1. Bies and Hansen Formulation
2.6.5.2. Dresden Group Formulation
2.6.6. Observed Hearing Loss
2.6.7. Occupational Noise Exposure Assessment
2.7. Hearing Damage Risk Criteria
2.7.1. Continuous Noise
2.7.2. Impulse Noise
2.7.3. Impact Noise
2.8. Implementing a Hearing Conservation Program
2.9. Hearing Protection Devices
2.9.1. Noise Reduction Rating, NRR
2.9.2. Noise Reduction Rating Subjective Fit, NRR(SF)
2.9.3. Noise Level Reduction Statistic, NRSAx
2.9.4. Calculation of Effective A-Weighted Sound Pressure Level Using Assumed Protection Value, APV
2.9.4.1. Octave Band Method
2.9.4.2. High, Medium, Low (HML) Method
2.9.4.3. Single Number Rating, SNR
2.9.5. Sound Level Conversion, SLC80
2.9.6. Standard Deviation
2.9.7. Personal Attenuation Rating (PAR)
2.9.8. Degradation of Effectiveness from Short Lapses
2.9.9. Overprotection
2.10. Speech Interference Criteria
2.10.1. Broadband Background Noise
2.10.2. Intense Tones
2.10.3. Speech Intelligibility Index and Speech Transmission Index
2.10.3.1. STI Calculation Procedure
2.10.3.2. STIPA Calculation Procedure
2.10.3.3. STITEL Calculation Procedure
2.10.3.4. SII Calculation Procedure
2.11. Psychological Effects of Noise
2.11.1. Noise as a Cause of Stress
2.11.2. Effect on Behaviour and Work Efficiency
2.11.3. Effect on Sleep
2.12. Ambient Sound Pressure Level Specification
2.12.1. Ambient Sound Recommendations for Classrooms
2.12.2. Noise Weighting Curves
2.12.2.1. NR Curves
2.12.2.2. NC Curves
2.12.2.3. NCB Curves
2.12.2.4. RC, Mark II Curves
2.12.2.5. RNC Curves
2.12.3. Speech Privacy
2.12.3.1. Measurement of Speech Privacy
2.13. Environmental Noise Criteria
2.13.1. A-Weighting Criteria
2.13.1.1. Low-Frequency Noise
2.13.1.2. Transportation Noise
2.13.1.3. Tonality
2.13.1.4. Impulsiveness
2.13.1.5. Intermittency
2.13.2. Comparison of Noise Weighting Curves with dBA Specifications
2.14. Environmental Noise Surveys
2.14.1. Measurement Locations
2.14.2. Duration of the Measurement Survey
2.14.3. Measurement Parameters and Procedures
2.14.4. Measurement Uncertainty
2.14.5. Noise Impact
3. Instrumentation for Noise Measurement and Analysis
3.1. Microphones
3.1.1. Condenser Microphones
3.1.2. Piezoelectric Microphones
3.1.3. MEMS Microphones
3.1.4. Pressure Response
3.1.5. Microphone Sensitivity and Dynamic Range
3.1.6. Field Effects and Calibration
3.1.7. Microphone Accuracy
3.1.8. Infrasound Sensors
3.1.9. Signal Conditioning
3.1.9.1. IEPE Sensors
3.1.9.2. TEDS Sensors
3.2. Sound Level Meters (SLMs)
3.3. Classes of Sound Level Meter
3.4. Sound Level Meter Calibration
3.4.1. Electrical Calibration
3.4.2. Acoustic Calibration
3.4.3. Measurement Accuracy
3.5. Noise Measurements Using Sound Level Meters
3.5.1. Microphone Mishandling
3.5.2. Sound Level Meter Amplifier Mishandling
3.5.3. Microphone and Sound Level Meter Response Characteristics
3.5.4. Background Noise
3.5.5. Wind Noise
3.5.6. Temperature
3.5.7. Humidity and Dust
3.5.8. Reflections from Nearby Surfaces
3.5.9. Time-Varying Sound
3.5.10. Sound Pressure Level Measurement
3.6. Data Loggers
3.7. Personal Sound Exposure Meters
3.8. Data Acquisition and Recording
3.9. Spectrum Analysers
3.9.1. Spectrograms
3.10. Sound Intensity Meters
3.10.1. Sound Intensity by the p − u Method
3.10.1.1. Accuracy of the p − u Method
3.10.2. Sound Intensity by the p − p Method
3.10.2.1. Accuracy of the p − p Method
3.10.3. Frequency Decomposition of the Intensity
3.10.3.1. Direct Frequency Decomposition
3.10.3.2. Indirect Frequency Decomposition
3.11. Sound Source Localisation
3.11.1. Near-Field Acoustic Holography (NAH)
3.11.1.1. Summary of the Underlying Theory
3.11.2. Statistically Optimised Near-Field Acoustic Holography (SONAH)
3.11.3. Helmholtz Equation Least Squares Method (HELS)
3.11.4. Beamforming
3.11.4.1. Summary of the Underlying Theory
3.11.5. Direct Sound Intensity Measurement
4. Sound Sources and Sound Power
4.1. Introduction
4.2. Simple Source
4.2.1. Pulsating Sphere
4.2.2. Fluid Mechanical Monopole Source
4.3. Dipole Source
4.3.1. Pulsating Doublet or Dipole (Far-Field Approximation)
4.3.2. Pulsating Doublet or Dipole (Near Field)
4.3.3. Oscillating Sphere
4.3.4. Fluid Mechanical Dipole Source
4.4. Quadrupole Source (Far-Field Approximation)
4.4.1. Lateral Quadrupole
4.4.2. Longitudinal Quadrupole
4.4.3. Fluid Mechanical Quadrupole Source
4.5. Line Source
4.5.1. Infinite Line Source
4.5.1.1. Incoherent Sources in a Line
4.5.1.2. Coherent Sources in a Line
4.5.2. Finite Line Source
4.5.2.1. Incoherent Sources in a Line
4.5.2.2. Coherent Sources in a Line
4.6. Piston in an Infinite Baffle
4.6.1. Far Field
4.6.2. Near Field On-Axis
4.6.3. Radiation Load of the Near Field
4.7. Incoherent Plane Radiator
4.7.1. Single Wall
4.7.2. Several Walls of a Building or Enclosure
4.8. Directivity
4.9. Reflection Effects
4.9.1. Simple Source Near a Reflecting Surface
4.9.2. Observer Near a Reflecting Surface
4.9.3. Observer and Source Both Close to a Reflecting Surface
4.10. Radiation Impedance
4.11. Relation between Sound Power and Sound Pressure
4.12. Radiation Field of a Sound Source
4.12.1. Free-Field Simulation in an Anechoic Room
4.12.2. Sound Field Produced in a Non-Anechoic Room
4.13. Determination of Sound Power Using Sound Intensity Measurements
4.13.1. Uncertainty in Sound Power Determined Using Sound Intensity Measurements
4.14. Determination of Sound Power Using Sound Pressure Measurements
4.14.1. Measurement in Free or Semi-Free Field
4.14.2. Measurement in a Diffuse Field
4.14.2.1. Substitution Method
4.14.2.2. Absolute Method
4.14.3. Field Measurement (ISO 3744, 2010)
4.14.3.1. Semi-Reverberant Field Measurements Using a Reference Source to Determine Room Absorption
4.14.3.2. Semi-Reverberant Field Measurements Using a Reference Source Substitution
4.14.3.3. Semi-Reverberant Field Measurements Using Two Test Surfaces
4.14.3.4. Near-Field Measurements
4.14.4. Measurement of the Total Sound Power of Multiple Sources Covering a Large Area
4.14.5. Gas Turbine Exhaust Sound Power Measurement
4.14.6. Wind Turbine Sound Power Measurements
4.14.7. Road Traffic Noise Measurement
4.14.8. Specialist Procedures for Other Noise Sources
4.14.9. High-Frequency Correction for Sound Power Level Measurements
4.14.10. Uncertainty in Sound Power Levels Determined Using Sound Pressure LevelMeasurements
4.15. Determination of Sound Power Using Surface Vibration Measurements
4.15.1. Uncertainty in Sound Power Measurements Determined Using Surface VibrationMeasurements
4.16. Uses of and Alternatives to Sound Power Information
4.16.1. Far Free Field
4.16.2. Near Free Field
4.16.3. Sound Pressure Levels at Operator Locations
5. Outdoor Sound Propagation and Outdoor Barriers
5.1. Introduction
5.2. Reflection and Transmission: Plane Interface between Two Different Media
5.2.1. Porous Ground
5.2.2. Plane Wave Reflection and Transmission
5.2.3. Spherical Wave Reflection at a Plane Interface Between Two Media
5.2.4. Effects of Turbulence
5.3. Sound Propagation Outdoors – General Concepts
5.3.1. Geometric Divergence, Adiv
5.3.2. Atmospheric Absorption, Aa
5.3.3. Ground Effect, Ag
5.3.4. Meteorological Effects, Amet
5.3.4.1. Uncertainty Bounds
5.3.4.2. Overview of Methods Used in Standard Propagation Models
5.3.4.3. Methods Using Linear Sonic Gradient Estimates
5.3.4.4. Methods Using Piecewise Linear Sonic Gradient Estimates
5.3.4.5. Calculation of Ray Path Lengths and Propagation Times
5.3.4.6. Ground-Reflected Rays – Single Ground Reflection
5.3.4.7. Ground-Reflected Rays – Multiple Ground Reflections
5.3.4.8. Low-Level Jets (LLJs)
5.3.4.9. Attenuation in the Shadow Zone (Negative Sonic Gradient)
5.3.5. Barrier Effects, Ab
5.3.5.1. Diffraction at the Edge of a Thin Sheet
5.3.5.2. Outdoor Barriers, Ray Paths Over the Top, Flat Ground
5.3.5.3. Outdoor Barriers, Ray Paths Over the Top, Sloping Ground
5.3.5.4. Outdoor Barriers, Ray Paths Around Barrier Ends, Flat Ground
5.3.5.5. Outdoor Barriers, Ray Paths Around Barrier Ends, Sloping Ground
5.3.5.6. Combining Contributions From All Paths Around a Barrier
5.3.5.7. Thick Barriers
5.3.5.8. Shielding by Terrain
5.3.5.9. Effects of Wind and Temperature Gradients
5.3.5.10. Barrier Insertion Loss (IL) Measurement
5.3.6. Miscellaneous Effects, Amisc
5.3.7. Low-Frequency Noise and Infrasound
5.3.8. Impulse Sound Propagation
5.4. Propagation Models in General Use
5.5. CONCAWE Noise Propagation Model
5.5.1. Spherical Divergence, K1
5.5.2. Atmospheric Absorption, K2
5.5.3. Ground Effects, K3
5.5.4. Meteorological Effects, K4
5.5.5. Source Height Effects, K5
5.5.6. Barrier Attenuation, K6
5.5.7. In-Plant Screening, K7
5.5.8. Vegetation Screening, Kv
5.5.9. Limitations of the CONCAWE Model
5.6. ISO 9613-2 (1996) Noise Propagation Model
5.6.1. Ground Effects, Ag
5.6.2. Meteorological Effects, Amet
5.6.3. Barrier Attenuation, Ab
5.6.4. Vegetation Screening, Af
5.6.5. Industrial Equipment Screening, Asite
5.6.6. Housing Screening, Ah
5.6.7. Effect of Reflections Other than Ground Reflections
5.6.8. Limitations of the ISO 9613-2 Model
5.7. NMPB-2008 Noise Propagation Model
5.7.1. Ground, Barrier and Terrain Attenuation, Ag+b
5.7.1.1. Mean Ground Plane
5.7.1.2. Ground Effect Factor, G
5.7.1.3. Ground Effect, No Diffraction: Homogeneous Atmosphere
5.7.1.4. Ground Effect: Downward Refraction, No Diffraction
5.7.1.5. Diffraction with No Ground Effect
5.7.1.6. Diffraction with Ground Effect
5.7.1.7. Vertical Edge Diffraction with Ground Effect
5.7.2. Reflections from Vertical Surfaces
5.7.3. Limitations of the NMPB-2008 Model
5.8. Required Input Data for the Various Propagation Models
5.8.1. CONCAWE
5.8.2. ISO 9613-2
5.8.3. NMPB-2008
5.9. Propagation Model Prediction Uncertainty
5.9.1. Type A Standard Uncertainty
5.9.2. Type B Standard Uncertainty
5.9.3. Combining Standard Uncertainties
5.9.4. Expanded Uncertainty
6. Sound in Enclosed Spaces
6.1. Introduction
6.1.1. Wall-Interior Modal Coupling
6.1.2. Sabine Rooms
6.1.3. Flat and Long Rooms
6.2. Low Frequencies
6.2.1. Rectangular Rooms
6.2.2. Cylindrical Rooms
6.3. Boundary between Low-Frequency and High-Frequency Behaviour
6.3.1. Modal Density
6.3.2. Modal Damping and Bandwidth
6.3.3. Modal Overlap
6.3.4. Crossover Frequency
6.4. High Frequencies, Statistical Analysis
6.4.1. Effective Intensity in a Diffuse Field
6.4.2. Energy Absorption at Boundaries
6.4.3. Air Absorption
6.4.4. Steady-State Response
6.5. Transient Response
6.5.1. Classical Description
6.5.2. Modal Description
6.5.3. Empirical Description
6.5.4. Mean Free Path
6.6. Measurement of the Room Constant
6.6.1. Reference Sound Source Method
6.6.2. Reverberation Time Method
6.7. Porous Sound Absorbers
6.7.1. Measurement of Absorption Coefficients
6.7.2. Single Number Descriptors for Absorption Coefficient
6.7.3. Porous Liners
6.7.4. Porous Liners with Perforated Panel Facings
6.7.5. Micro-Perforated Panels and Sheets
6.7.6. Acoustic Metamaterials
6.7.6.1. Layered Fibrous Material
6.7.6.2. Porous Concrete
6.7.6.3. Functionally Graded Materials
6.7.7. Sound-Absorption Coefficients of Materials in Combination
6.8. Panel Sound Absorbers
6.8.1. Empirical Method
6.8.2. Analytical Method
6.9. Flat and Long Rooms
6.9.1. Flat Room with Specularly Reflecting Floor and Ceiling
6.9.2. Flat Room with Diffusely Reflecting Floor and Ceiling
6.9.3. Flat Room with Specularly and Diffusely Reflecting Boundaries
6.9.4. Long Room with Specularly Reflecting Walls
6.9.5. Long Room: Circular Cross-Section, Diffusely Reflecting Wall
6.9.6. Long Room with Rectangular Cross-Section
6.10. Applications of Sound Absorption
6.10.1. Relative Importance of the Reverberant Field
6.10.2. Reverberation Control
7. Partitions, Enclosures and Indoor Barriers
7.1. Introduction
7.2. Sound Transmission through Partitions
7.2.1. Bending Waves
7.2.2. Transmission Loss, TL (or Sound Reduction Index, R)
7.2.2.1. Measurement of Transmission Loss Outside of a Laboratory
7.2.2.2. Single Number Ratings for Transmission Loss of Partitions
7.2.2.3. Uncertainty in TL and R Measurements
7.2.3. Impact Isolation Measurement According to ASTM Standards
7.2.3.1. Laboratory Measurements
7.2.3.2. Measurement of the Effectiveness of Floor Coverings
7.2.3.3. Field Measurements
7.2.3.4. Uncertainty According to ASTM E492-09 (2016)
7.2.4. Impact Isolation Measurement According to ISO Standards
7.2.4.1. Laboratory Measurements
7.2.4.2. Measurement of the Effectiveness of Floor Coverings
7.2.4.3. Field Measurements
7.2.4.4. Additional Impact Spectrum Adaptation Term
7.2.4.5. Uncertainty According to ISO 12999-1 (2020)
7.2.5. Recommended Sound and Impact Isolation Values for Apartment and Office Buildings
7.2.6. Panel Transmission Loss (or Sound Reduction Index) Estimates
7.2.6.1. Sharp’s Prediction Scheme for Isotropic Panels
7.2.6.2. Davy’s Prediction Scheme for Isotropic Panels
7.2.6.3. ISO 12354-1 (2017) Prediction Scheme for Isotropic Panels
7.2.6.4. Thickness Correction for Isotropic Panels
7.2.6.5. Orthotropic Panels
7.2.7. Sandwich Panels
7.2.8. Double Wall Transmission Loss
7.2.8.1. Sharp Model for Double Wall TL
7.2.8.2. Davy Model for Double Wall TL
7.2.8.3. Model from ISO 12354-1 (2017)
7.2.8.4. Stud Spacing Effect in Walls with Wooden Studs
7.2.8.5. Staggered Studs
7.2.8.6. Panel Damping
7.2.8.7. Effect of Cavity Material Flow Resistance
7.2.8.8. Multi-Leaf and Composite Panels
7.2.8.9. TL Properties of Some Common Stud Wall Constructions
7.2.9. Triple Wall Sound Transmission Loss
7.2.10. Sound-Absorptive Linings
7.2.11. Common Building Materials
7.3. Noise Reduction versus Transmission Loss
7.3.1. Combined Transmission Loss
7.3.2. Flanking Transmission
7.4. Enclosures
7.4.1. Noise Inside Enclosures
7.4.2. Noise Outside Enclosures
7.4.3. Personnel Enclosures
7.4.4. Enclosure Windows
7.4.5. Enclosure Leakages
7.4.6. Enclosure Access and Ventilation
7.4.7. Enclosure Vibration Isolation
7.4.8. Enclosure Resonances
7.4.9. Close-Fitting Enclosures
7.4.10. Partial Enclosures
7.4.11. Enclosure Performance Measurement
7.5. Indoor Barriers
7.6. Pipe Lagging
7.6.1. Porous Material Lagging
7.6.2. Impermeable Jacket and Porous Blanket Lagging
8. Muffling Devices
8.1. Introduction
8.2. Measures of Performance
8.3. Design for a Required Performance
8.4. Diffusers as Muffling Devices
8.5. Classification of Muffling Devices
8.6. Acoustic Impedance
8.7. Lumped Element Devices
8.7.1. Impedance of an Orifice or a Short Narrow Duct
8.7.1.1. Lumped Element Analysis
8.7.1.2. Transmission Line Analysis
8.7.1.3. Impedance of a Perforated Plate
8.7.1.4. End Correction
8.7.1.5. Acoustic Resistance
8.7.2. Impedance of a Volume
8.8. Reactive Devices
8.8.1. Acoustical Analogues of Kirchhoff’s Laws
8.8.2. Side Branch Resonator
8.8.2.1. End Corrections
8.8.2.2. Quality Factor
8.8.2.3. Insertion Loss Due to Side Branch
8.8.2.4. Transmission Loss Due to Side Branch
8.8.3. Resonator Mufflers
8.8.3.1. Resonator Mufflers For Tonal Control
8.8.3.2. Resonator Mufflers for Broadband Noise Control
8.8.4. Expansion Chamber
8.8.4.1. Insertion Loss
8.8.4.2. Transmission Loss
8.8.5. Small Engine Exhaust
8.8.6. Low-Pass Filter
8.9. 4-Pole Method
8.9.1. Acoustic Performance Metrics
8.9.2. 4-Pole Matrices of Various Acoustic Elements
8.9.3. Straight Duct
8.9.4. Quarter-Wavelength Tube (QWT)
8.9.5. Helmholtz Resonators
8.9.6. Sudden Expansion and Contraction
8.9.7. Simple Expansion Chamber (SEC)
8.9.8. Double-Tuned Expansion Chamber (DTEC)
8.9.9. Concentric Tube Resonator (CTR)
8.9.10. Exhaust Gas Temperature Variations
8.9.11. Source and Termination Impedances
8.10. Lined Duct Attenuation of Sound
8.10.1. Locally-Reacting and Bulk-Reacting Liners
8.10.2. Liner Specifications
8.10.3. Lined Duct Mufflers
8.10.3.1. Flow Effects
8.10.3.2. Temperature Effects
8.10.3.3. Higher Order Mode Propagation
8.10.4. Cross-Sectional Discontinuities
8.10.5. Splitter Mufflers
8.11. Insertion Loss of Duct Bends or Elbows
8.12. Insertion Loss of Unlined Ducts
8.13. Effect of Duct End Reflections
8.14. Pressure Loss Calculations for Muffling Devices
8.14.1. Pressure Losses Due to Friction
8.14.2. Dynamic Pressure Losses
8.14.3. Splitter Muffler Pressure Loss
8.14.4. Circular Muffler Pressure Loss
8.14.5. Staggered Splitter Pressure Loss
8.15. Flow-Generated Noise
8.15.1. Straight, Unlined Air Duct Noise Generation
8.15.2. Mitred Bend Noise Generation
8.15.3. Splitter Muffler Self-Noise Generation
8.15.4. Grille Noise
8.15.5. Exhaust Stack Pin Noise
8.15.6. Self-Noise Generation of Air Conditioning System Elements
8.16. Duct Break-Out Noise
8.16.1. Break-Out Sound Transmission
8.16.2. Break-In Sound Transmission
8.17. Lined Plenum Attenuator
8.17.1. Wells’ Method
8.17.2. ASHRAE (2015) Method
8.17.3. More Complex Methods
8.18. Water Injection
8.19. Directivity of Exhaust Ducts
8.19.1. Hot Exhausts Subject to Cross-Flow
9. Vibration Control
9.1. Introduction
9.2. Vibration Isolation
9.2.1. Single-Degree-of-Freedom Systems
9.2.1.1. Surging in Coil Springs
9.2.2. Four-Isolator Systems
9.2.3. Two-Stage Vibration Isolation
9.2.4. Practical Considerations for Isolators
9.2.5. Moving a Machine to a Different Location on a Floor
9.2.5.1. Effect of Stiffness of Equipment Mounted on Isolators
9.2.5.2. Effect of Stiffness of Foundations
9.2.5.3. Superimposed Loads on Isolators
9.3. Types of Isolators
9.3.1. Rubber
9.3.2. Metal Springs
9.3.3. Cork
9.3.4. Felt
9.3.5. Air Springs
9.4. Vibration Absorbers, Tuned Mass Dampers and Vibration Neutralisers
9.4.1. Vibration Absorbers
9.4.2. Vibration Neutralisers
9.5. Vibration Measurement
9.5.1. Acceleration Transducers
9.5.1.1. Sources of Measurement Error
9.5.1.2. Sources of Error in the Measurement of Transients
9.5.1.3. Accelerometer Calibration
9.5.1.4. Accelerometer Mounting
9.5.1.5. Piezoresistive Accelerometers
9.5.2. Velocity Transducers
9.5.3. Laser Vibrometers
9.5.4. Instrumentation Systems
9.5.5. Units of Vibration
9.6. Vibration Criteria
9.7. Damping of Vibrating Surfaces
9.7.1. Damping Methods
9.7.2. When Damping is Effective and Ineffective
9.8. Measurement of Damping
10. Sound Power and Sound Pressure Level Estimation Procedures
10.1. Introduction
10.2. Fan Noise
10.3. Air Compressors
10.3.1. Small Compressors
10.3.2. Large Compressors (Sound Pressure Levels within the Inlet and Exit Piping)
10.3.2.1. Centrifugal Compressors
10.3.2.2. Rotary (or Axial) Compressors
10.3.2.3. Reciprocating Compressors
10.3.3. Large Compressors (Exterior Sound Pressure Levels)
10.3.3.1. Rotary and Reciprocating Compressors
10.3.3.2. Centrifugal Compressors (Casing Noise)
10.3.3.3. Centrifugal Compressors (Unmuffled Air Inlet Noise)
10.4. Compressors for Chillers and Refrigeration Units
10.5. Cooling Towers
10.6. Pumps
10.7. Jets
10.7.1. General Estimation Procedures
10.7.2. General Jet Noise Control
10.8. Control Valves for Gases
10.8.1. Internal Sound Power Generation
10.8.2. Internal Sound Pressure Level
10.8.3. External Sound Pressure Level
10.8.4. Noise-Reducing Trim
10.8.5. High Exit Velocities
10.8.6. Control Valves for Steam
10.8.7. Gas and Steam Control Valve Noise Reduction
10.9. Control Valves for Liquids
10.9.1. Liquid Control Valve Noise Reduction
10.10. Gas Flow in Pipes
10.11. Boilers
10.12. Gas and Steam Turbines
10.13. Reciprocating Piston Engines (Diesel or Gas)
10.13.1. Exhaust Noise
10.13.2. Casing Noise
10.13.3. Inlet Noise
10.14. Furnace Noise
10.15. Electric Motors
10.15.1. Small Electric Motors (below 300 kW)
10.15.2. Large Electric Motors (above 300 kW)
10.16. Generators
10.17. Gears
10.18. Power Transformers
10.19. Large Wind Turbines (Rated Power Greater than or Equal to 0.2 MW)
10.20. Transportation Noise
10.20.1. Road Traffic Noise
10.20.1.1. CNOSSOS Model (European Commission)
10.20.1.2. UK DoT model (CoRTN)
10.20.1.3. United States FHWA Traffic Noise Model (TNM)
10.20.1.4. Other Models
10.20.1.5. Accuracy of Traffic Noise Models
10.20.2. Rail Traffic Noise
10.20.2.1. Nordic Prediction Model (1996)
10.20.2.2. European Commission Model
10.20.2.3. UK Department of Transport Model
10.20.3. Aircraft Noise
11. Practical Numerical Acoustics
11.1. Introduction
11.2. Low-Frequency Region
11.2.1. Helmholtz Method
11.2.2. Boundary Element Method (BEM)
11.2.2.1. Direct Method
11.2.2.2. Indirect Method
11.2.2.3. Meshing
11.2.2.4. Problem Formulation
11.2.3. Rayleigh Integral Method
11.2.4. Finite Element Analysis (FEA)
11.2.4.1. Pressure Formulated Acoustic Elements
11.2.4.2. Practical Aspects of Modelling Acoustic Systems with FEA
11.2.5. Numerical Modal Analysis
11.2.6. Modal Coupling Using MATLAB®
11.2.6.1. Acoustic Potential Energy
11.3. High-Frequency Region: Statistical Energy Analysis
11.3.1. Subsystem Responses
11.3.2. Subsystem Input Impedances
11.3.3. Subsystem External Input Power
11.3.4. Damping Loss Factors (DLFs)
11.3.5. Modal Densities
11.3.5.1. Random Boundary Impedance
11.3.6. Coupling Loss Factors (CLFs)
11.3.6.1. Tunnelling Phenomena
11.3.6.2. Coupling Loss Factors for Point Connections
11.3.6.3. Coupling Loss Factors for Structural Line Connections
11.3.6.4. Coupling Loss Factors for Area Connections
12. Frequency Analysis
12.1. Introduction
12.2. Digital Filtering
12.2.1. Octave and 1/3-Octave Filter Rise Times and Settling Times
12.3. Advanced Frequency Analysis
12.3.1. Relationships Between Various Spectral Quantities
12.3.2. Auto Power Spectrum and Power Spectral Density
12.3.3. Linear Spectrum
12.3.4. Leakage
12.3.5. Windowing
12.3.5.1. Amplitude Scaling to Compensate for Window Effects
12.3.5.2. Window Function Coefficients
12.3.5.3. Power Correction and RMS Calculation
12.3.6. Sampling Frequency and Aliasing
12.3.7. Overlap Processing
12.3.8. Zero Padding
12.3.9. Uncertainty Principle
12.3.10. Time Synchronous Averaging and Synchronous Sampling
12.3.11. Hilbert Transform
12.3.12. Cross Spectrum
12.3.13. Coherence
12.3.14. Coherent Output Power
12.3.15. Frequency Response (or Transfer) Function
12.3.16. Convolution
12.3.16.1. Continuous Functions
12.3.16.2. Sampled Data
12.3.17. Auto-Correlation and Cross-Correlation Function Estimates
12.3.18. Maximum Length Sequence (MLS)
A. Review of Relevant Linear Matrix Algebra
A.1. Addition, Subtraction and Multiplication by a Scalar
A.2. Multiplication of Matrices
A.3. Matrix Transposition
A.4. Matrix Determinants
A.5. Rank of a Matrix
A.6. Positive and Nonnegative Definite Matrices
A.7. Eigenvalues and Eigenvectors
A.8. Orthogonality
A.9. Matrix Inverses
A.10. Singular Value Decomposition
B. Wave Equation Derivation
B.1. Conservation of Mass
B.2. Euler’s Equation
B.3. Equation of State
B.4. Wave Equation (Linearised)
C. Properties of Materials
D. Acoustical Properties of Porous Materials
D.1. Flow Resistance and Flow Resistivity
D.2. Parameters for Characterising Sound Propagation in Porous Media
D.3. Sound Reduction Due to Propagation through a Porous Material
D.4. Measurement of Absorption Coefficients of Porous Materials
D.4.1. Measurement Using the Moving Microphone Method
D.4.2. Measurement Using the Two-Microphone Method
D.4.3. Measurement Using the Four-Microphone Method
D.4.3.1. Amplitude Transmission Coefficient, Anechoic Termination
D.4.3.2. Absorption Coefficient, Anechoic Termination
D.4.3.3. Absorption Coefficient, Rigid Termination
D.4.3.4. Complex Wavenumber, Impedance and Density of the Test Sample
D.4.3.5. Correction of the Measured Transfer Functions Due to Microphone Differences
D.4.4. In-Situ Measurement
D.4.5. Reverberation Room Measurement
D.5. Calculation of Absorption Coefficients of Porous Materials
D.5.1. Porous Materials with a Backing Cavity
D.5.2. Multiple Layers of Porous Liner Backed by an Impedance
D.5.3. Porous Liner Covered with a Limp Impervious Layer
D.5.4. Porous Liner Covered with a Perforated Sheet
D.5.5. Porous Liner with a Limp Impervious Layer and a Perforated Sheet
E. Partial Coherence Combination of Sound Pressures
F. Files for Use with This Book
F.1. Table of Files for Use with This Book
References
Index