Noise Control: From Concept to Application

Cover
Half Title
Title Page
Copyright Page
Dedication
Contents
Preface
1. Fundamentals
	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
	1.3. Acoustical Standards and Software
	1.4. Acoustic Field Variables
		1.4.1. Variables
		1.4.2. Magnitudes
		1.4.3. The Speed of Sound
		1.4.4. Acoustic Potential Function and the Wave Equation
		1.4.5. 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
	1.6. Mean Square Quantities and Amplitudes
	1.7. Energy Density
	1.8. Sound Intensity
	1.9. Sound Power
	1.10. Decibels
	1.11. Spectra
		1.11.1. Frequency Analysis
	1.12. Combining Sound Pressures
		1.12.1. Coherent Sounds
		1.12.2. Incoherent Sounds
		1.12.3. Subtraction of Sound Pressure Levels
		1.12.4. Combining Level Reductions
	1.13. Impedance
		1.13.1. Mechanical Impedance, Z m
		1.13.2. Specific Acoustic Impedance, Z s
		1.13.3. Acoustic Impedance, Z A
	1.14. Additional Problems
2. Loudness, Descriptors of Noise, Noise Criteria and Instrumentation
	2.1. Introduction
	2.2. Loudness
		2.2.1. Comparative Loudness and the Phon
		2.2.2. Low-Frequency Loudness
		2.2.3. Relative Loudness and the Sone
		2.2.4. Weighting Networks
	2.3. Descriptors of Noise
		2.3.1. Equivalent Continuous Sound Pressure Level, Leq
		2.3.2. A-Weighted Equivalent Continuous Sound Pressure Level, L Aeq
		2.3.3. Noise Exposure Level, L EX,8h or L ex or L ep'd
		2.3.4. A-Weighted Sound Exposure, E A, T
		2.3.5. A-Weighted Sound Exposure Level, L AE or SEL
		2.3.6. Day-Night Average Sound Level, L dn or DNL
		2.3.7. Community Noise Equivalent Level, L den or CNEL
		2.3.8. Statistical Descriptors
		2.3.9. Other Descriptors, L max, L peak, L Imp
	2.4. Hearing Loss
	2.5. Hearing Damage Risk
		2.5.1. Requirements for Speech Recognition
		2.5.2. Quantifying Hearing Damage Risk
		2.5.3. United States Standard Formulation
		2.5.4. Occupational Noise Exposure Assessment
		2.5.5. Impulse and Impact Noise
	2.6. Implementing a Hearing Conservation Programme
	2.7. Speech Interference Criteria
	2.8. Psychological Effects of Noise
		2.8.1. Noise as a Cause of Stress
		2.8.2. Effect on Behaviour and Work Efficiency
	2.9. Ambient Sound Pressure Level Specification
		2.9.1. Noise Weighting Curves
			2.9.1.1. NR Curves
			2.9.1.2. NC Curves
			2.9.1.3. NCB Curves
			2.9.1.4. RC, Mark II Curves
		2.9.2. Comparison of Noise Weighting Curves with dBA Specifications
		2.9.3. Speech Privacy
	2.10. Environmental Noise Criteria
		2.10.1. A-Weighting Criteria
	2.11. Environmental Noise Surveys
		2.11.1. Measurement Locations
		2.11.2. Duration of the Measurement Survey
		2.11.3. Measurement Parameters
		2.11.4. Measurement Uncertainty
		2.11.5. Noise Impact
	2.12. Measuring Instrumentation
		2.12.1. Microphones
			2.12.1.1. Microphone Sensitivity
		2.12.2. Sound Level Meters
			2.12.2.1. Calibration
			2.12.2.2. Measurement Accuracy
		2.12.3. Statistical Analysers
		2.12.4. Personal Exposure Meter
		2.12.5. Data Acquisition and Recording
		2.12.6. Spectrum Analysers
		2.12.7. Sound Intensity Meters
		2.12.8. Acoustic Cameras
	2.13. Additional Problems
3. Sound Sources and Sound Power Measurement
	3.1. Introduction
	3.2. Simple Source
	3.3. Dipole Source
	3.4. Quadrupole Source
		3.4.1. Lateral Quadrupole
		3.4.2. Longitudinal Quadrupole
	3.5. Line Source
		3.5.1. Infinite Line Source
		3.5.2. Finite Line Source
	3.6. Piston in an Infinite Baffle
	3.7. Incoherent Plane Radiator
		3.7.1. Single Wall
		3.7.2. Several Walls of a Building or Enclosure
	3.8. Radiation Field of a Sound Source
	3.9. Directivity
	3.10. Reflection Effects
		3.10.1. Simple Source Near a Reflecting Surface
		3.10.2. Observer Near a Reflecting Surface
		3.10.3. Observer and Source Both Close to a Reflecting Surface
	3.11. Determination of Sound Power
		3.11.1. Measurement in Free or Semi-Free Field
		3.11.2. Measurement in a Diffuse Field
			3.11.2.1. Substitution Method
			3.11.2.2. Absolute Method
		3.11.3. Field Measurement
			3.11.3.1. Semi-Reverberant Field Measurements Using a Reference Source to Determine Room Absorption
			3.11.3.2. Semi-Reverberant Field Measurements Using a Reference Source Substitution
			3.11.3.3. Semi-Reverberant Field Measurements Using Two Test Surfaces
			3.11.3.4. Near-Field Measurements
		3.11.4. Uncertainty in Sound Power Measurements
	3.12. Additional Problems
4. Sound Propagation Outdoors
	4.1. Introduction
	4.2. Methodology
	4.3. Geometric Divergence, Adiv
	4.4. Atmospheric Absorption, Aatm
	4.5. Ground Effects, Agr
		4.5.1. Excess Attenuation Using Simply Hard or Soft Ground
		4.5.2. Excess Attenuation Using the Plane Wave Method
	4.6. Meteorological Effects, Amet
		4.6.1. Attenuation in the Shadow Zone (Negative Sonic Gradient)
	4.7. CONCAWE Propagation Model
		4.7.1. Geometrical Divergence, K 1
		4.7.2. Atmospheric Absorption, K 2
		4.7.3. Ground Effects, K 3
		4.7.4. Meteorological Effects, K 4
		4.7.5. Source Height Effects, K 5
		4.7.6. Barrier Attenuation, K 6
		4.7.7. In-Plant Screening, K 7
		4.7.8. Vegetation Screening, K v
		4.7.9. Limitations of the CONCAWE Model
	4.8. ISO 9613-2 (1996) Noise Propagation Model
		4.8.1. Ground Effects, Agr
		4.8.2. Meteorological Effects, Amet
		4.8.3. Source Height Effects
		4.8.4. Barrier Attenuation, Abar
		4.8.5. In-Plant Screening, Asite
		4.8.6. Housing Screening, Ahous
		4.8.7. Vegetation Screening, Afol
		4.8.8. Effect of Reflections Other Than Ground Reflections
		4.8.9. Limitations of the ISO9613-2 Model
	4.9. Propagation Model Prediction Uncertainty
		4.9.1. Type A Standard Uncertainty
		4.9.2. Type B Standard Uncertainty
		4.9.3. Combining Standard Uncertainties
		4.9.4. Expanded Uncertainty
	4.10. Additional Problems
5. Sound Absorbing Materials
	5.1. Introduction
	5.2. Flow Resistance and Resistivity
	5.3. Sound Propagation in Porous Media
	5.4. Measurement of Absorption Coefficients of Porous Materials
		5.4.1. Measurement Using the Moving Microphone Method
		5.4.2. Measurement Using the Two-Microphone Method
	5.5. Calculation of Statistical Absorption Coefficients of Some Porous Material Configurations
		5.5.1. Porous Liner with a Backing Cavity
		5.5.2. Porous Liner Covered with a Limp Impervious Layer
		5.5.3. Porous Liner Covered with a Perforated Sheet
		5.5.4. Porous Liner with a Limp Impervious Layer and a Perforated Sheet
	5.6. Measurements of the Sabine Absorption Coefficient and Room Constant
		5.6.1. Reference Sound Source Method
		5.6.2. Reverberation Time Method
		5.6.3. Measurement of ¯for a Particular Material
	5.7. Panel Sound Absorbers
	5.8. Noise Reduction Coefficient (NRC)
	5.9. Sound Absorption Coefficients of Materials in Combination
	5.10. Reverberation Control
	5.11. Additional Problems
6. Sound in Rooms
	6.1. Introduction
	6.2. Low Frequency Behaviour
	6.3. Bound 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. Cross-Over Frequency
	6.4. High-Frequency Behaviour
		6.4.1. Relation between Source Sound Power and Room Sound Pressure Level
		6.4.2. Relation between Room Absorption and Reverberation Time
	6.5. Flat Room with Diffusely Reflecting Surfaces
	6.6. Additional Problems
7. Partitions, Enclosures and Barriers
	7.1. Introduction
	7.2. Sound Transmission through Partitions
		7.2.1. Bending Waves
		7.2.2. Transmission Loss
		7.2.3. Single-Leaf Panel Transmission Loss Calculation
		7.2.4. Double Wall Transmission Loss
			7.2.4.1. Staggered Studs
			7.2.4.2. Panel Damping
		7.2.5. Triple Wall Sound Transmission Loss
		7.2.6. Sound-Absorptive Linings
		7.2.7. Common Building Materials
	7.3. Composite Transmission Loss
	7.4. Enclosures
		7.4.1. Enclosure Leakages (Large Enclosures)
		7.4.2. Enclosure Access and Ventilation
		7.4.3. Enclosure Vibration Isolation
	7.5. Barriers
		7.5.1. Diffraction at the Edge of a Thin Sheet
		7.5.2. Outdoor Barriers
			7.5.2.1. Thick Barriers
			7.5.2.2. Shielding by Terrain
			7.5.2.3. ISO 9613-2 Approach to Barrier Insertion Loss Calculations
		7.5.3. Indoor Barriers
	7.6. Additional Problems
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. Impedances of Reactive Muffler Components
		8.7.1. Impedance of an Orifice or Short, Narrow Tube
			8.7.1.1. End Correction
			8.7.1.2. Acoustic Resistance
		8.7.2. Impedance of a Volume
	8.8. Reactive Mufflers
		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. Power Dissipated
			8.8.2.4. Insertion Loss Due to a Side Branch
			8.8.2.5. Transmission Loss Due to a Side Branch
		8.8.3. Expansion Chamber
			8.8.3.1. Insertion Loss
			8.8.3.2. Transmission Loss
		8.8.4. Lowpass Filter
	8.9. Dissipative Mufflers
		8.9.1. Liner Specification
		8.9.2. Lined Duct Design
			8.9.2.1. Temperature Effects
			8.9.2.2. Higher Order Mode Propagation
		8.9.3. Inlet Attenuation
		8.9.4. Cross-Sectional Discontinuities
		8.9.5. Splitter Mufflers
	8.10. Insertion Loss of Duct Bends or Elbows
	8.11. Insertion Loss of Unlined Ducts
	8.12. Effect of Duct End Reflections
	8.13. Pressure Loss Calculations for Muffling Devices
		8.13.1. Pressure Losses Due to Friction
		8.13.2. Dynamic Pressure Losses
		8.13.3. Splitter Muffler Pressure Loss
		8.13.4. Circular Muffler Pressure Loss
		8.13.5. Staggered Splitter Pressure Loss
	8.14. Flow-Generated Noise
		8.14.1. Straight, Unlined Air Duct Noise Generation
		8.14.2. Mitred Bend Noise Generation
		8.14.3. Splitter Muffler Self-Noise Generation
		8.14.4. Exhaust Stack Pin Noise
		8.14.5. Self-Noise Generation of Air Conditioning System Elements
	8.15. Duct Break-Out Noise
		8.15.1. Break-Out Sound Transmission
		8.15.2. Break-In Sound Transmission
	8.16. Lined Plenum Attenuator
		8.16.1. Wells' Method
		8.16.2. ASHRAE (2015) Method
	8.17. Directivity of Exhaust Ducts
	8.18. Additional Problems
A. Properties of Materials
References
Index