Page 13 - The Master Handbook Of Acoustics

xii CONTENTS

Open-Cell Foams 192
Drapes as Sound Absorbers 193
Carpet as Sound Absorber 196
Effect of carpet type on absorbance 199
Effect of carpet underlay on absorbance 200
Carpet absorption coefficients 200
Sound Absorption by People 200
Absorption of Sound in Air 203
Low-Frequency Absorption by Resonance 203
Diaphragmatic Absorbers 205
Polycylindrical Absorbers 209
Poly Construction 212
Membrane Absorbers 213
Helmholtz Resonators 215
Perforated Panel Absorbers 218
Slat Absorbers 224
Placement of Materials 225
Reverberation Time of Helmholtz Resonators 225
Taming room modes 226
Increasing Reverberation Time 229
Modules 229

Chapter 10 Reflection of Sound 235

Reflections from Flat Surfaces 235
Doubling of Pressure at Reflection 237
Reflections from Convex Surfaces 237
Reflections from Concave Surfaces 237
Reflections from Parabolic Surfaces 238
Reflections inside a Cylinder 240
Standing Waves 240
Reflection of Sound from Impedance
Irregularities 240
The Corner Reflector 243
Echo-Sounding 243
Perceptive Effects of Reflections 244