Acoustics for Engineers - Troy Lectures

Preface

Contents

1 Introduction

1.1 Definition of Three Basic Terms

1.2 Specialized Areas within Acoustics

1.3 About the History of Acoustics

1.4 Relevant Quantities in Acoustics

1.5 Some Numerical Examples

1.6 Levels and Logarithmic Frequency Intervals

1.7 Double-Logarithmic Plots

2 Mechanic and Acoustic Oscillations

2.1 Basic Elements of Linear, Oscillating, Mechanic Systems

2.2 Parallel Mechanic Oscillators

2.3 Free Oscillations of Parallel Mechanic Oscillators

2.4 Forced Oscillation of Parallel Mechanic Oscillators

2.5 Energies and Dissipation Losses

2.6 Basic Elements of Linear, Oscillating, Acoustic Systems

2.7 The Helmholtz Resonator

3 Electromechanic and Electroacoustic Analogies

3.1 The Electromechanic Analogies

3.2 The Electroacoustic Analogy

3.3 Levers and Transformers

3.4 Rules for Deriving Analogous Electric Circuits

3.5 Synopsis of Electric Analogies of Simple Oscillators

3.6 Circuit Fidelity, Impedance Fidelity and Duality

3.7 Examples of Mechanic and Acoustic Oscillators

4 Electromechanic and Electroacoustic Transduction

4.1 Electromechanic Couplers as Two- or Three-Port Elements

4.2 The Carbon Microphone – A Controlled Coupler

4.3 Fundamental Equations of Electroacoustic Transducers

4.4 Reversibility

4.5 Coupling of Electroacoustic Transducers to the Sound Field

4.6 Pressure and Pressure-Gradient Receivers

4.7 Further Directional Characteristics

4.8 Absolute Calibration of Transducers

5 Magnetic-Field Transducers

5.1 The Magnetodynamic Transduction Principle

5.2 Magnetodynamic Sound Emitters and Receivers

5.3 The Electromagnetic Transduction Principle

5.4 Electromagnetic Sound Emitters and Receivers

5.5 The Magnetostrictive Transduction Principle

5.6 Magnetostrictive Sound Transmitters and Receivers

6 Electric-Field Transducers

6.1 The Piezoelectric Transduction Principle

6.2 Piezoelectric Sound Emitters and Receivers

6.3 The Electrostrictive Transduction Principle

6.4 Electrostrictive Sound Emitters and Receivers

6.5 The Dielectric Transduction Principle

6.6 Dielectric Sound Emitters and Receivers

6.7 Further Transducer and Coupler Principles

7 The Wave Equation in Fluids

7.1 Derivation of the One-Dimensional Wave Equation

7.2 Three-Dimensional Wave Equation in Cartesian Coordinates

7.3 Solutions of the Wave Equation

7.4 Field Impedance and Power Transport in Plane Waves

7.5 Transmission-Line Equations and Re.ectance

7.6 The Acoustic Measuring Tube

8 Horns and Stepped Ducts

8.1 Webster’s Differential Equation – the Horn Equation

8.2 Conical Horns

8.3 Exponential Horns

8.4 Radiation Impedances and Sound Radiation

8.5 Steps in the Area Function

8.6 Stepped Ducts

9 Spherical Sound Sources and Line Arrays

9.1 Spherical Sound Sources of 0th Order

9.2 Spherical Sound Sources of 1st Order

9.3 Higher-Order Spherical Sound Sources

9.4 Line Arrays of Monopoles

9.5 Analogy to Fourier Transforms as Used in Signal Theory

9.6 Directional Equivalence of Sound Emitters and Receivers

10 Piston Membranes, Diffraction and Scattering

10.1 The Rayleigh Integral

10.2 Fraunhofer’s Approximation

10.3 The Far Field of Piston Membranes

10.4 The Near Field of Piston Membranes

10.5 General Remarks on Diffraction and Scattering

11 Dissipation, Re.ection, Refraction, and Absorption

11.1 Dissipation During Sound Propagation in Air

11.2 Sound Propagation in Porous Media

11.3 Reflection and Refraction

11.4 Wall Impedance and Degree of Absorption

11.5 Porous Absorbers

11.6 Resonance Absorbers

12 Geometric Acoustics and Diffuse Sound Fields

12.1 Mirror Sound Sources and Ray Tracing

12.2 Flutter Echoes

12.3 Impulse Responses of Rectangular Rooms

12.4 Di.use Sound Fields

12.5 Reverberation-Time Formulae

12.6 Application of Diffuse Sound Fields

13 Isolation of Air- and Structure-Borne Sound

13.1 Sound in Solids – Structure-Borne Sound

13.2 Radiation of Airborne Sound by Bending Waves

13.3 Sound-Transmission Loss of Single-Leaf Walls

13.4 Sound-Transmission Loss of Double-Leaf Walls

13.5 The Weighted Sound-Reduction Index

13.6 Isolation of Vibrations

13.7 Isolation of Floors with Regard to Impact Sounds

14 Noise Control – A Survey

14.1 Origins of Noise

14.2 Radiation of Noise

14.3 Noise Reduction as a System Problem

14.4 Noise Reduction at the Source

14.5 Noise Reduction Along the Propagation Paths

14.6 Noise Reduction at the Receiver’s End

15 Appendices

15.1 Complex Notation for Sinusoidal Signals

15.2 Complex Notation for Power and Intensity

15.3 Supplementary Textbooks for Self Study

15.4 Letter Symbols, Notations and Units

Index