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Introduction to Acoustics

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22.4.5 Combinations of Elementary Structures ..................... 926<br />

22.5 Structural–Acoustic Coupling ............................................ 926<br />

22.5.1 Longitudinally Vibrating Bar Coupled <strong>to</strong> an External Fluid . 927<br />

22.5.2 Energetic Approach <strong>to</strong> Structural–Acoustic Systems ........ 932<br />

22.5.3 Oscilla<strong>to</strong>r Coupled <strong>to</strong> a Tube of Finite Length ............... 934<br />

22.5.4 Two-Dimensional Elas<strong>to</strong>–Acoustic Coupling ................. 936<br />

22.6 Damping .................................................................. 940<br />

22.6.1 Modal Projection in Damped Systems ........................ 940<br />

22.6.2 Damping Mechanisms in Plates .............................. 943<br />

22.6.3 Friction ......................................................... 945<br />

22.6.4 Hysteretic Damping ............................................ 947<br />

22.7 Nonlinear Vibrations ..................................................... 947<br />

22.7.1 Example of a Nonlinear Oscilla<strong>to</strong>r ............................ 947<br />

22.7.2 Duffing Equation .............................................. 949<br />

22.7.3 Coupled Nonlinear Oscilla<strong>to</strong>rs ................................ 951<br />

22.7.4 Nonlinear Vibrations of Strings ............................... 955<br />

22.7.5 Review of Nonlinear Equations for Other Continuous<br />

Systems ......................................................... 956<br />

22.8 Conclusion. Advanced Topics ............................................ 957<br />

References ........................................................................ 958<br />

23 Noise<br />

George C. Maling, Jr. ............................................................. 961<br />

23.0.1 The Source–Path–Receiver Model ............................ 961<br />

23.0.2 Properties of Sound Waves .................................... 962<br />

23.0.3 Radiation Efficiency ........................................... 963<br />

23.0.4 Sound Pressure Level of Common Sounds ................... 965<br />

23.1 Instruments for Noise Measurements ................................... 965<br />

23.1.1 <strong>Introduction</strong> .................................................... 965<br />

23.1.2 Sound Level .................................................... 966<br />

23.1.3 Sound Exposure and Sound Exposure Level ................. 967<br />

23.1.4 Frequency Weightings ......................................... 967<br />

23.1.5 Octave and One-Third-Octave Bands ........................ 967<br />

23.1.6 Sound Level Meters ............................................ 968<br />

23.1.7 Multichannel Instruments .................................... 969<br />

23.1.8 Sound Intensity Analyzers .................................... 969<br />

23.1.9 FFT Analyzers ................................................... 969<br />

23.2 Noise Sources ............................................................. 970<br />

23.2.1 Measures of Noise Emission .................................. 970<br />

23.2.2 International Standards for the Determination of Sound<br />

Power ........................................................... 973<br />

23.2.3 Emission Sound Pressure Level ............................... 977<br />

23.2.4 Other Noise Emission Standards .............................. 978<br />

23.2.5 Criteria for Noise Emissions ................................... 979<br />

23.2.6 Principles of Noise Control .................................... 981<br />

23.2.7 Noise From Stationary Sources ................................ 984<br />

23.2.8 Noise from Moving Sources ................................... 987<br />

Detailed Contents 1163<br />

Detailed Cont.

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