Noise Control, 2nd Edition

5

Sound-Absorbing Materials: Properties and their Measurement

LEARNING OBJECTIVES

In this chapter, the reader is introduced to:

• concepts of flow resistance and how it relates to sound absorption;

• statistical sound absorption coefficient and its calculation and measurement for porous materials;

• Sabine absorption coefficient and its measurement;

• use of porous materials in sound absorption; and

• panel absorbers.

5.1 Introduction

The ability of materials to absorb sound can be quantified in terms of their absorption coefficient, which can vary from 0.001 for highly reflective materials to 1 for very absorptive materials. There are two types of absorption coefficients that are commonly used: the statistical absorption coefficient, ${\alpha }_{st}$ and ...