柔性材料振动吸声理论

Preface

Chapter 1 Properties and Testing Methods of Sound Absorption

Materials

1.1 Properties of Sound Absorption Materials

1.1.1 Porous Absorptive Materials

1.1.2 Resonant or Reactive Absorbers

1.2 Measurement of Sound Absorption Materials

1.2.1 Measurement of Acoustic Parameters

1.2.2 Measurement Method and Apparatus of Air Permeability and Yield Strength of Fiber Layer

Chapter 2 Introduction of Conventional Sound Absorption Theories

2.1 Sound Transmission of Porous Materials

2.1.1 Sound Transmission in the Round Pipe and Narrow Slit

2.1.2 Porous Sound Absorption Materials

2.1.3 Porous Sound Absorption Materials in Several Specific Cases

2.2 Sound Absorption in Diaphragmatic Absorber

Chapter 3 An Empirical Formula for Sound Absorption of Fibrous Materials

3.1 Introduction

3.2 Sound Absorption Spectra of Several Sound Absorption Fibrous Materials

3.3 Sound Absorption Spectrum Formula

3.4 Discussion on Sound Absorption Spectrum Formula

3.5 Maximal Sound Absorption Coefficient： Material Air Permeability and Sound Absorption Coefficient Formula

3.6 Conclusion

Chapter 4 Analysis on Sound Absorption Principle of Thin Fibrous Layer

4.1 Introduction

4.2 Acoustic Analysis of Thin Fibrous Layer by Application of Membrane Vibration Theory

4.3 The Proofs of Fabric Vibration Sound Absorption Theory

4.3.1 Determination of the % Open Area of Fabric

4.3： 2 Relation Between Fabric Structure Character-istic and Specifi Acoustic Impedance

4.3.3 Analysis on Sound Absorption Characteristics Using the Micropore Viscous Sound Absorption Theory

4.3.4 Application of the Resonance Theory

4.4 Conclusion

Chapter 5 Vibration Sound Absorption Model of Porous Material

5.1 Introduction

5.2 Sound Absorption Model and Theoretical Formula of Porous Materials

5.3 Discussion and Verification

5.3.1 The Relation between the Material Structural Parameters and the Maximal Sound Absorption Coefficient

5.3.2 The Formula of Sound Absorption Spectrum

5.4 Conclusion

Chapter 6 Elastic Sound Absorption Principle of Fibrous Material

6.1 Introduction

6.2 Vibration Sound Absorption Theory

6.3 The Comparing and Discussing of the Theory Results and Testing Results

Chapter 7 Resonance Frequency Formula of Densely Porous Material and Sound Absorption Coefficient Formula of Flexible Membrane

7.1 Introduction

7.2 Resonance Sound Absorption Frequency of Densely Porous Material

7.2.1 Micro-perforation Sound Absorption Theory

7.2.2 Resonance Sound Absorption Model of Densely Porous Material

7.2.3 End Correction of Micro Perforation

7.2.4 Comparison and Discussion of Actual Measured Results

7.2.5 Situation of Larger and Smaller Perforation

7.3 Flexible Membrane Sound Absorption Model and Sound Absorption Coefficient Formula

7.3.1 Sound Absorption Model of Flexible Membrane

7.3.2 Verification and Discussion of the Sound Absorption Coefficient Formula of Flexible Membrane

7.4 Conclusion

The sound absorption material plays an important role in room acoustic and environmental noise control.In general.thetraditional sound absorption material is the porous material，perforated panel，plate and membrane material.British great classical physicist Lord Rayleigh put forward the micropore viscosity sound absorption theory of porous material more than100 years ago.Zwikker and Kosten made further development ofthe theory 50 years ago.Although the research has undergone formore than 100 years，a majority of the scientists still follow suchconcept，the pore space of the porous material and perforatedmaterial produces the viscous effect on the fluctuating air of thesound wave，with which the sound energy is converted into heatenergy.