<p><p>This textbook presents the fundamentals of engineering acoustics and examines in depth concepts within the domain that apply to reducing noise, measuring noise, and designing microphones and loudspeakers. The book particularly emphasizes the physical principles used in designing miniature micr
Physical Approach to Engineering Acoustics (Mechanical Engineering Series)
β Scribed by Ronald N. Miles
- Publisher
- Springer
- Year
- 2023
- Tongue
- English
- Leaves
- 406
- Edition
- 2
- Category
- Library
No coin nor oath required. For personal study only.
β¦ Synopsis
This updated edition adds new material on the acoustics of mufflers and ducts, including a new analysis on sound propagation in a duct having a cross sectional area that varies in the direction of the duct length. The textbook retains its class-tested fundamentals of engineering acoustics and examination of in-depth concepts within the domains that apply to reducing noise, measuring noise, and designing microphones and loudspeakers. The book particularly emphasizes the physical principles used in designing miniature microphones. These devices are used in billions of electronic products, most visibly, cell phones and hearing aids, and enable countless other applications. Distinct from earlier books on this topic that take the view of the electrical engineer analyzing mechanical systems using electric circuit analogies. This text uses Newtonian mechanics as a more appropriate paradigm for analyzing these mechanical systems and in so doing provides a more direct method of modeling. Written at a level appropriate for upper-division undergraduate and graduate courses, and enhanced with end-of-chapter problems and MatLab routines, the book is ideal as a core text for students interested in engineering acoustics in ME, EE, and physics programs, as well as a reference for engineers and technicians working in the huge global industry of miniature microphone design.
β¦ Table of Contents
Preface
Contents
Nomenclature
1 Analysis of Acoustic Signals
1.1 Some BasicsβMeasures of Sound
1.2 One-Third Octave Band Levels
1.3 A-Weighted Sound Levels
1.4 Narrowband Signal Analysis
1.5 Power Spectral Density by the Finite Fourier Transform
1.6 Spectral Analysis of Measured Time Series
1.7 Sound Level Calculations from Narrowband Power Spectra
1.8 The ``Slow'' Fourier Transform: Least Squares Extraction of a Harmonic Signal
1.9 Frequency Response of Linear Systems with Random Input
1.10 InputβOutput Relationships for a Linear System
1.11 Spectral Approach to Evaluating the Convolution Integral
1.12 Example: FFT for Response of a Spring/Mass/Damper
1.13 Example: Numerical Differentiation and Integration Using the FFT
1.14 FFT and iFFT to Estimate the Fourier Transform for Complex Functions
1.15 Problems
2 One Dimensional Sound Fields
2.1 Newton's Second Law
2.2 Conservation of Mass
2.3 Equation of State
2.4 Solutions for Some Simple Fields
2.5 Sound Intensity and the Sound Absorption Coefficient
2.6 d'Alembert's Solution
2.7 Sound in an Infinite Tube
2.8 Problems
3 Sound Transmission Loss
3.1 The Mass Law
3.2 Random Incidence Sound Transmission Loss
3.3 Transmission Loss Calculations Using Transfer Matrices
3.4 Transfer Matrix for a Solid Element
3.5 Transfer Matrix for an Air Gap
3.6 Air Gap with Non-normal Incident Sound
3.7 Double Walls
3.7.1 Simple Air Gap
3.7.2 Low Frequencies
3.7.3 Slightly Higher FrequenciesβDouble Wall Resonance
3.7.4 Very High Frequencies
3.8 Analysis of Double Walls with Mechanical Coupling
3.9 Problems
References for Chapter 3
4 Analysis of Mufflers and Ducts
4.1 The Junction of Two Pipes
4.2 The Expansion Muffler
4.3 The Helmholtz Resonator
4.4 Side Branches
4.5 General Side Branch
4.6 Simple Pipe Side Branch
4.7 Sound in Tubes of Varying Cross-Sectional Area
4.7.1 Conical Horn
4.7.2 Assemble Conical Elements to Model a Tube with Arbitrary Cross-Sectional Area
4.7.3 Solving for the Pressure and Velocity Within the Domain
4.7.4 The Exponential Horn
4.7.5 Numerical Example for a Non-uniform Duct
4.8 Problems
Reference for Chapter 4
5 Sound Radiation in Three Dimensions
5.1 Wave Equation in Three Dimensions
5.2 Sound Intensity of Spherical Waves
5.3 Sound Radiation by a Simple Source
5.4 Sound Field Inside a Pulsating Sphere
5.5 Simple Model of Sound Radiation from a Loudspeaker
5.6 The Image Source
5.6.1 Periodic Frequency Response Due to Reflections
5.7 The Acoustic Dipole
5.8 The Line Source
5.9 Surface Source
5.10 Sound Radiation from a Piston in a Baffle
5.11 Single Piston
5.12 Piston Vibration
5.13 Multiple Piston Radiators
5.14 Analysis and Design of Loudspeakers in Vented Boxes
5.14.1 Loudspeaker Diaphragm in a Closed Box
5.14.2 Diaphragm Force Due to Back Volume of Air
5.14.3 Effect of the Air in the Vent
5.14.4 Response Due to Harmonic Sound Fields
5.14.5 Sound Radiation from Loudspeakers in Vented Boxes
5.15 Problems
6 Computer-Aided Acoustics
6.1 The Green's Function
6.2 Green's Function for Infinite Half-Space Bounded by an Infinite Rigid Plane
6.3 Integral Equation for the General Sound Radiation Problem
6.4 Numerical Solution
6.5 Effect of Boundary Impedance
6.6 Sound Field Due to a Point Source in an Enclosure
6.7 Calculation of the Pressure at an Arbitrary Point in Space
6.8 Approximate Evaluation of Integrals
6.8.1 Elements that Are Sufficiently Separated: Estimation Using Midpoints
6.8.2 Estimation of Bll
6.8.3 Estimation of Cll
6.8.4 Computer-Aided Design Model to Specify Geometry
6.8.5 Evaluation of Singular Integrals for Cll
6.9 Numerical Results
6.9.1 Sound Inside a Rectangular Tube
6.9.2 Sound Inside a Radially Oscillating Sphere
6.9.3 Sound Radiation from a Radially Oscillating Cylinder
6.9.4 Sound Radiation from a Radially Oscillating Cylinder
6.10 Problems
References for Chapter 6
7 Modal Solutions for the Sound in Enclosures
7.1 Natural Frequencies and Eigenfunctions for the Rectangular Enclosure
7.2 Solution for the Pressure Field
7.3 Numerical Results
8 Geometrical Room Acoustics
8.1 Relation Between Energy Density and Intensity
8.2 Effect of Sound Absorption Coefficient on Steady-State Sound Fields
8.3 Effect of Sound Absorption Coefficient on Decaying Sound Fields
8.4 Problems
9 Effects of Viscosity
9.1 Basic Equations for Sound in a Viscous Fluid
9.2 Viscous Flow in One Dimension
9.3 Squeeze Film Damping in a Compressible Fluid in Two Dimensions
9.3.1 Limiting Cases at Low and High Frequencies
9.3.2 Numerical Results
9.4 Viscous Force on an Oscillating Cylinder
9.5 Viscous Acoustic Excitation of a Thin Beam Having Circular Cross Section
9.6 Solutions for the Acoustic Response
9.6.1 Response of an Infinitely Long Uniform Fiber
9.6.2 Response of a Fiber of Finite Length
9.7 Pressure and Flow Around a Periodic Array of Thin Beams Including Viscosity and Compressibility
9.7.1 Fourier Transform Solution for the Velocities and Pressure
9.7.2 Numerical Evaluation
9.7.3 Numerical Example
9.8 Sound Pressure and Viscous Flow Around a Periodic Array of Thin Beams
9.8.1 Numerical Results
9.9 Problems
References for Chapter 9
10 Acoustic Sensing
10.1 Mechanical Sensitivity of a Microphone Diaphragm
10.2 Diaphragm with No Vent
10.3 Diaphragm Force Due to Back Volume of Air
10.4 Effect of the Air in the Vent
10.5 Response Due to Harmonic Sound Fields
10.6 The Microphone Package as a Helmholtz Resonator
10.7 An Important Note on the Ideal Diaphragm Properties
10.8 Damping Due to the Vent
10.9 Acoustic Radiation Loading on the Diaphragm
10.10 Numerical Examples
10.11 Analysis of Thermal-Mechanical Noise in a Pressure-Sensing Microphone
10.12 Limiting Case of Thermal-Mechanical Noise in an Ideal Pressure-Sensing Microphone
10.13 Thermal Response of a Velocity Driven Spring/Mass
10.13.1 Application to a Hair for Sensing Sound
10.13.2 Thermal Noise Response Increases with the Number of Degrees of Freedom
10.14 Viscous Flow-Induced Response to Sound and Signal to Noise Ratio, SNR
10.15 Effect of Sound Angle of Incidence on a Pressure Microphone
10.16 Acceleration Sensitivity
10.17 Basics of Directional Microphones
10.17.1 First-Order Directional Microphones
10.17.2 Second-Order Directional Microphones
10.18 The Ribbon Microphone
10.19 Effect of Gain Errors on Directivity Index
10.20 Empirical Microphone Compensation for Desired Directivity
10.21 Noise in Directional Microphones
10.22 Directivity Index by Integration in the Wave Vector Domain
10.23 Acoustic Particle Velocity Estimation Using a Pressure Differential Microphone
10.23.1 Measurement of Acoustic Particle Velocity
10.23.2 Pressure Gradient and Velocity Microphones
10.23.3 Measurement Error
10.24 Two-Microphone Intensity Measurement
10.25 Problems
References for Chapter 10
11 Electronic Transduction for Acoustic Sensors
11.1 Electrical Sensitivity of a Microphone
11.1.1 Microphone Sensitivity Using a Constant Charge, High Impedance Voltage Amplifier
11.1.2 Effect of Buffer Amplifier Input ImpedanceβParasitic Capacitance
11.1.3 Microphone Sensitivity Using a Constant Voltage Bias
11.2 Effect of the Electronic Circuit on the Diaphragm Mechanical Response
11.2.1 Electric Force Due to Constant Charge
11.2.2 Electric Force Due to Constant Voltage
11.3 Optimum Capacitance for Sensitivity and Stability
11.4 Sound Input-Referred Noise
11.5 Effects of Electronic Noise and Stray Capacitance
11.6 Noise Analysis of a Charge Amplifier
11.7 Microphone Equivalent Input Noise Including Electronics
11.8 Electrodynamic Microphones
12 Estimation of Capacitance
12.1 Coulomb's Law and the Electric Potential
12.2 Integral Equation Relating Charge and Potential
12.3 Numerical Evaluation for Three-Dimensional Domains
12.4 Potential Energy for a Distribution of Charge Densities
12.5 Equation of Motion for a System Having a Single Degree of Freedom
12.6 Example of a Softening Electrode: Parallel Plate
12.7 Example of a Stiffening Electrode: Electrostatic Pendulum
12.8 Example of an Adjustable Electrode: Electrostatic Pendulum β¦
12.9 Example of an Adjustable Electrode: A Bistable Electrostatic Pendulum
12.10 Electronic Sensitivity
12.11 Compliant Repulsive Actuator
References for Chapter 12
13 Parameter Identification of Acoustic Systems
13.1 Least Squares Model of a Complex Transfer Function with Real Unknowns
13.2 Accounting for an Unknown Time Delay in H
13.3 Examples
13.4 Problems
References for Chapter 13
Appendix A The Use of Complex Notation
Appendix B Introduction to Probability and Random Processes
B.1 Ergodicity
B.2 Probability
B.3 Probability Distribution Function
B.4 Probability Density Functions
B.5 Expected Values in Terms of Probability Density Functions
B.6 The Characteristic Function
B.7 The Log Characteristic Function
B.8 The Gaussian Probability Density
B.9 Properties of Gaussian Random Variables
B.10 Jointly Distributed Random Variables
B.11 Conditional Probability Density
B.12 Functions of Random Variables
B.13 Estimating Probability Densities from Discrete Data
Appendix C The Mean Square Response of a Spring/Mass/Damper
C.1 Response of a One Degree of Freedom System
C.2 Mean Square Response by Time Domain Integration
C.3 Frequency Domain Approach
Appendix D Analysis of Circuit Noise
D.1 General Operational Amplifier Noise Analysis
D.2 Noise Prediction for a Specific Design
Appendix E Some Useful Formulas
References for Appendices
Index
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