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Predicting Outdoor Sound

Early Observations A Brief Survey of Outdoor Sound Attenuation Mechanisms Data Illustrating Ground Effect Propagation from a Fixed Jet Engine Source Propagation over Discontinuous Ground Data Illustrating the Combined Effects of Ground and Meteorology More Fixed Jet Engine Data Road Traffic Noise Propagation over Flat Terrain under Strong Temperature Inversion Meteorological Effects on Railway Noise Propagation over Flat Terrain Road Traffic Noise Propagation in a Valley Classification of Meteorological Conditions for Outdoor Sound Prediction Typical Sound Speed Profiles Linear-Logarithmic Representations of Sound Speed Profiles Air Absorption Note References The Propagation of Sound near Ground Surfaces in a Homogeneous Medium Introduction A Point Source Above Smooth Flat Acoustically Soft Ground The Sound Field Above a Locally Reacting Ground The Sound Field Above a Layered Extended-Reaction Ground Surface Waves Above Porous Ground Experimental Data and Numerical Predictions The Sound Field Due to a Line Source Near the Ground References Predicting Effects of Source Characteristics Introduction Sound Fields Due to Dipole Sources Near the Ground The Horizontal Dipole The Vertical Dipole An Arbitrarily Orientated Dipole The Sound Field due to an Arbitrarily Orientated Quadrupole Railway Noise Directivity and Prediction Source Characteristics of Road Traffic Basic Formulae and Parameters Directivity Corrections Other Corrections and Limitations Source Characteristics of Wind Turbines Sound-generation Mechanisms Typical Spectra of Large Horizontal Axis Wind Turbines Horizontal and Vertical Directivity Amplitude Modulation References Numerical Methods Based on Time-Domain Approaches Introduction An Efficient Complete Finite-Difference Time-Domain Model for Outdoor Sound Propagation Sound Propagation Equations Numerical Discretization Homogeneous and Still Propagation Medium Inhomogeneous Media Moving Medium Staggered-in-time Collocated-in-time Prediction-Step Staggered-In-time Numerical Accuracy and Stability Modelling Propagation in a Moving Unbounded Atmosphere Modelling Finite Impedance Boundary Conditions Impedance Plane Approach Ground Interaction Modelling by Including a Layer of Soil Poro-Rigid Frame Model Poro-Elastic Frame Models Long-Distance Sound Propagation Prediction Based on FDTD Moving Frame FDTD Hybrid Modelling: Combining FDTD with GFPE Advantages of the GFPE Method Complex Source Region, Simplified Receiver Region Procedure for One-way Coupling from FDTD to GFPE Numerical Example Computational Cost Reduction References Predicting the Acoustical Properties of Ground Surfaces Introduction Predicting Ground Impedance Empirical and Phenomenological Models Microstructural Models Using Idealized Pore Shapes Approximate Models for High Flow Resistivities Relaxation Models Relative Influence of Microstructural Parameters Physical Inadmissibility of Semi-Empirical Models Predicting Effects of Surface Roughness Boss and Stochastic Models Impedance Models Including Rough Surface Effects Hard Rough Surfaces Rough Finite Impedance Surfaces Modified ‘Boss’ and Empirical Models for Regularly Spaced Roughness Elements Multiple Scattering Models A Roughness Spectrum Model Propagation over Rough Seas Effective Impedance of Rough Sea Surfaces Predicted Propagation of Offshore Piling Noise Predicted Rough Sea Effects on Sonic Booms Predicting Effects of Ground Elasticity Coupling from Airborne Sound to Structures and Ground Vibration Biot-Stoll Theory Numerical Calculations of Acoustic–Seismic Coupling Fast Field Program for Layered Air-Ground Systems (FFLAGS)Example Predictions of Low-Frequency Effects References Measurements of the Acoustical Properties of Ground Surfaces and Comparisons with Models Impedance Measurement Methods Impedance Tube Impedance Meter Non-Invasive Measurements Direct Measurement of Reflection Coefficient Impedance Deduction from Short-Range Measurements Model Parameter Deduction from Short-Range Propagation Data A Template Method for Impedance Deduction Effective Flow Resistivity Classification Direct Impedance Deduction Comparisons of Impedance Spectra with Model Predictions Fits to Short-Range Propagation Data Using Impedance Models Short-Range Grassland Data and Fits Fits to Data Obtained over Forest Floors, Gravel and Porous Asphalt Railway Ballast Measured Flow Resistivities and Porosities Comparison of Template and Direct Deduction Methods over Grassland Spatial and Seasonal Variations in Grassland Impedance Predicted Effects of Spatial Variation Measured Effects of Varying Moisture Content Influence of Water Content on ‘Fast’ and Shear Wave Speeds Measured Spatial and Seasonal Variations Ground Effect Predictions based on Fits to Short-Range Level Difference Spectra On the Choice of Ground Impedance Models for Outdoor Sound Prediction Measured and Predicted Surface Roughness Effects Roughness-Induced Ground Effect Excess Attenuation Spectra for Random and Periodic Roughness Roughness-Induced Surface Waves Outdoor Measurements of the Influence of Roughness on Ground Effect Measured and Predicted Effects of Ground Elasticity Elasticity Effects on Surface Impedance Ground Vibrations Due to Airborne Explosions Non-Linear Interaction with Porous Ground Deduction of Soil Properties from Measurements of A/S Coupling References Influence of Source Motion on Ground Effect and Diffraction Introduction A Monopole Source Moving at Constant Speed and Height Above a Ground Surface The Sound Field of a Source Moving with Arbitrary Velocity Comparison with Heuristic Calculations Point Source Moving at Constant Speed and Height Parallel to a Rigid Wedge Kinematics Diffracted Pressure for a Source in Uniform Motion Source Moving Parallel to a Ground Discontinuity Introduction Uniform Motion Parallel to a Single Discontinuity Source Moving at Constant Height Parallel to a Rigid Barrier Above the Ground Barrier over Hard Ground Barrier over Impedance Ground Source Moving over Externally Reacting Ground References Predicting Effects of Mixed Impedance Ground Introduction Single Impedance Discontinuity De Jong’s Semi-Empirical Method Modified De Jong Method Rasmussen’s Method Multiple Impedance Discontinuities An Extended De Jong Method The nMID (Multiple Impedance Discontinuities) Method Nyberg’s Method The Boundary Element Method Comparisons of Predictions with Data Single Impedance Discontinuity Impedance Strips Refraction above Mixed Impedance Ground Predicting Effects of Ground Treatments near Surface Transport Roads Sound Propagation from a Road over Discontinuous Impedance Predicted Effects of Replacing ‘Hard’ by ‘Soft’ Ground Near a Road Predicting Effects of Low Parallel Walls and Lattices Tramways Railways Porous Sleepers and Porous Slab Track Predicting Meteorological Effects on the Insertion Loss of Low Parallel Walls Configuration and Geometry Numerical Methods Meteorological Effects Predicting Effects of Variability in Downward-Refraction and Ground Impedance Introduction Meteorological Data and Processing Grassland Impedance Data Sound Propagation Modelling and Numerical Parameters Detailed Analysis of a Temporal Sequence Statistical Analysis of Temporal Variation over a Full Year Spectral Variation Variation in A-Weighted Pink Noise Convergence to Yearly L Aeq Conclusions References Predicting the Performance of Outdoor Noise Barriers Introduction Analytical Solutions for the Diffraction of Sound by a Barrier Formulation of the Problem The MacDonald Solution The Hadden and Pierce Solution for a Wedge Approximate Analytical Formulation Empirical Formulations for Studying the Shielding Effect of Barriers The Sound Attenuation by a Thin Plane on the Ground Noise Reduction by a Finite-Length Barrier Adverse Effect of Gaps in Barriers The Acoustic Performance of an Absorptive Screen Gabion Barriers Numerical Predictions of Comparative Acoustical Performance Laboratory Measurements on Porous-Stone Gabions Outdoor Measurements on a Gabion Barrier Optimizing Gabion Barriers for Noise Reduction Other Factors in Barrier Performance Barrier Shape Meteorological Effects on Barrier Performance Rough and Soft Berms Berms vs Barriers in Wind Sonic Crystal Noise Barriers Predicted Effects of Spectral Variations in Train Noise During Pass-by References Predicting Effects of Vegetation, Trees and Turbulence Measured Effects of Vegetation Influence of Vegetation on Soil Properties Measurements of Sound Transmission through Vegetation Measured Attenuation due to Trees, Shrubs and Hedges Predicting Sound Transmission through Vegetation Ground Effect with Plants and Vegetation Models for Foliage Effects Empirical Models Scattering Models Reduction of Coherence by Scattering Predictions of Ground Effect, Scattering and Foliage Attenuation Sound Propagation in Crops Sound Propagation in Forests Influence of Ground on Propagation Through Arrays of Vertical Cylinders Laboratory Data Combining ‘Sonic Crystal’ and Ground Effects Numerical Design of Tree Belts for Traffic Noise Reduction Measured and Predicted Effects of Irregular Spacing in the Laboratory Reflection from Forest Edges Meteorological Effects on Sound Transmission Through Trees Combined Effects OF Trees, Barriers and Meteorology Turbulence and its Effects Turbulence Mechanisms Models for Turbulence Spectra Clifford and Lataitis Prediction of Ground Effect in Turbulent Conditions Ostashev et al. Improvements on the Clifford and Lataitis Approach Height Dependence of Turbulence Turbulence-Induced Phase and Log-Amplitude Fluctuations Scattering by Turbulence Decrease in Sound Levels due to Turbulence Measurement of Turbulence Inclusion of Atmospheric Turbulence in the Fast Field Program Comparisons with Experimental Data Including Turbulence in FDTD Calculations Equivalence of Turbulence and Scattering Influences on Coherence References Ray Tracing, Analytical and Semi-empirical Approximations for A-Weighted Levels Ray Tracing Linear Sound Speed Gradients and Weak Refraction Approximations for A-Weighted Levels and Ground Effect Optimization in the Presence of Weak Refraction and Turbulence Ground Effect Optimization Integral Expressions for A-Weighted Mean Square Sound Pressure Approximate Models for Ground Impedance Effects of Weak Refraction Approximations for Excess Attenuation Variable Porosity or Thin Layer Ground Rough Ground Smooth High Flow Resistivity Ground Numerical Examples and Discussion Comparison with Data: Avon Jet Engine Source Sensitivity to Spectrum, Source Height and Distance Variation with Distance Effects of Refraction Concluding Remarks A Semi-Empirical Model for A-Weighted Sound Levels at Long Range References Engineering Models Introduction ISO 9613–2 Description Basic Equations Geometrical Divergence Atmospheric Absorption Ground Effect Screening Meteorological Correction General Critique CONCAWE Introduction Basis and Provisions of Scheme Criticisms of CONCAWE Calculation of Road Traffic Noise (CRTN)Introduction Basic Equations L 10 Levels Corrections for Mean Traffic Speed, Percentage of Heavy Vehicles and Gradient Correction for Type of Road Surface Distance Correction Ground Cover Correction Screening Correction Site Layout Segments and Road Junctions Calculation of Railway Noise (CRN)NORD2000 HARMONOISE Introduction and Background General Methodology Basic Equations Identification of Propagation Planes Recommended Numerical Techniques Meteorological Conditions Frequency Resolution Long-term Integrated Levels Validation Analytical Point-to-point Model Introduction Methodology for Combining Ground and Barrier Effect Ground Reflection Model Sound Diffraction Model Single Diffraction Multiple Diffractions Transition Model Refraction Coherence Losses Scattering by Turbulence The Environmental Noise Directive (END) Scheme (CNOSSOS-EU)Ground Effect Criticisms Performance of Railway Noise Prediction Schemes in High-Rise Cities Performance of Engineering Models in a Complex Road Traffic Noise Example Site and Models Approximating the Berm Slope Road Traffic Source Power Modelling Daytime vs Nighttime Measurements and Predictions Model Performance Predicting Wind Turbine Noise An Untypical Industrial Source Complex Meteorologically Induced Propagation Effects Ground Effect for Wind Turbine Sound Propagation Propagation over Non-Flat Terrain Prediction Requirements for Outdoor Sound Auralization Introduction Simulating Outdoor Attenuation by Filters Auralization of a Noise Abatement Based on a Priori Recordings References

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