Page 205 - The Master Handbook Of Acoustics

180 CHAPTER NINE

E
S

F

G
H

A K

I J
B

D
C

FIGURE 9-1

A sound ray impinging on an acoustical material on a masonry wall undergoes reflection
from three different surfaces and absorption in the air and two different materials, with
different degrees of refraction at each interface. In this chapter, the absorbed compo-
nent is of chief interest.

strikes the surface of the concrete blocks, two things happen: a com-
ponent is reflected (B), and the ray is bent strongly downward as it
enters the much denser concrete blocks. Of course, there is further
heat loss (G) within the concrete blocks. As the ray travels on, getting
weaker all the time, it strikes the concrete-air boundary and under-
goes another reflection (C) and refraction (D) with heat lost (I, J, and
K) in three media.