Question

In which of the following absorbents, absorption takes place due to the frictional losses occurring due to the to and fro movement of the air contained in the material caused by the sound waves?

(a) Cavity resonators

(b) Resonant panels

(c) Porous materials

(d) Composite types

I have been asked this question during an interview.

Question is from Acoustics topic in chapter Acoustics and Ventilation of Construction & Building Materials

Answer 1

The correct answer is (c) Porous materials

The explanation is: In porous materials, absorption takes place due to the frictional losses occurring due to the to and fro movement of the air contained in the material caused by the sound waves. These materials absorb sound generally in higher frequencies.