Question

your boss asks you to design a room to be as soundproof as possible and provides you with three samples of material. the only information on each samples label is the materials coefficient of absorption. the coefficient of absorption listed on sample a is 30%, on sample b is 47%, and on sample c is 62%. which material do you recommend and why?
a) sample c, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.
b) sample a, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.
c) sample c, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.
d) sample a, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the largest.

Explanation:

A material's sound absorption coefficient measures the percentage of incident sound energy it absorbs. Higher absorption means less sound energy is reflected. For soundproofing, we need the material that reflects the least sound energy. Sample C has the highest absorption coefficient (62%), so it reflects the smallest percentage of incident sound energy (100% - 62% = 38%), which is better for soundproofing.

Answer:

A) Sample C, because the percentage of the energy in an incident wave that remains in a reflected wave from this material is the smallest.