Active Noise Control Primer

1. Introduction.- Welcome to the World of Active Noise Control!.- Summary.- Do I Have to Read the Whole Book?.- What Is Active Noise Control?.- Adaptive Feedforward Active Control Noise.- Advanced Reading.- 2. Background: Fundamentals of Sound.- What Is Sound?.- What Is Noise?.- Quantifying Sound Levels.- Sound Waves.- Frequency Analysis.- Sine Waves.- Fourier Analysis.- Harmonics.- 1. Anything that Rotates.- 2. Many Devices Which Use Mains Electricity.- 3. Devices Which Are Driven Beyond Their Capabilities.- Human Perception of Sound.- Acceptable Sound Levels.- 3. Fundamentals of Noise Control.- Prerequisite Discussion: Power and Impedance.- The Magnitude of Acoustic Power.- Decibel Units for Acoustic Power.- Power, Pressure, and Hearing Loss.- Real and Imaginary Impedancec.- What Is Noise Control?.- What Is Passive Noise Control.- What is Active Noise Control?.- 4. Free Space Noise Control.- Passive Noise Control Approaches.- Control Control Approaches.- 5. Enclosed Space Noise Control.- Where Does the Sound Come From?.- How Does the Sound Get Out Again?.- How Does the Sound Field Arrange Itself?.- Passive Noise Control Approaches.- Active Noise Control Approaches.- 6. Control of Sound Propagation in Ducts.- Sound Fields in Ducts.- Modes in Ducts.- Impedance in Ducts.- Passive Noise Control Approaches.- Sidebranch Resonator.- Expansion Chamber.- Helmholtz Filter.- Dissipative Passive Control Techniques.- Active Noise Control Approaches.- Reference and Error Signal Quality.- Reference Sensor/Control Source Separation Distance.- Control Source Position in the Duct.- Duct Response Characteristics.- 7. Active Noise Controller Overview.- Some Important Facts.- Digital System Requirements.- Controller Output (Digital Control Filter) Requirements.- Adaptive Algorithm Requirements.- 8. Controller Fundamentals.- General Control System Outlines and Definitions.- Physical System Limitations.- Interfacing a Digital System.- Background.- Required Additions for Digital Control.- Overview of the Controller.- Controller Component 1: The Digital Filter.- What Is a Digital Filter?.- Specifying the "Appropriate" Digital Filter.- Specifying the Digital Filter Length.- Controller Component 2: The Adaptive Algorithm.- Background: Making Use of Adaptive Signal Processing.- Gradient Descent Algorithms.- Evaluating the Gradient.- The Convergence Coefficient.- Quantization Errors and Leakage.- Slowing Down the Algorithm to Improve Performance.- Controller Component 3: Cancellation Path Modeler.- Selecting the Sample Rate.- So What Is the Optimum Sample Rate?.