Transmission of Sound in Built-Up Structures

Abstract

Maximum permissible noise and vibration levels are often required for most types of machinery, vehicles, and buildings.

Problems

16.1

Derive Eq. (16.1).

16.2

An acoustic source is located in a room. Determine the modal energy of the acoustic field in the room. The equivalent absorption area in the room is A. Assume that the field is induced by a number of sources scattered in the room. The power spectral density of the total volume velocity of the sources is $G_Q$ and is constant.

16.3

Derive the sound pressure level difference between the rooms 1 and 3 shown in Fig. 16.6 by using the appropriate coupling loss factors.

16.4

Derive the coupling loss factor $\eta _{13}$ between the rooms 1 and 3 shown in Fig. 16.6. The coupling loss factor $\eta _{13}$ defines the nonresonant transmission through a panel having the sound transmission coefficient $\tau$.

16.5

Derive the modal density in a narrow cavity, height d,  having the dimensions $L_x$ and $L_y$ for $f < c/(2d)$. Compare Eq. (16.60).

16.6

Determine the coupling loss factor between two plates. Consider only flexural waves. Only rotation at the junction. Compare Eq. (16.60).

16.7

Determine the coupling loss factor between the two rods shown in Fig. 16.12. Consider only longitudinal waves in the rods. Compare Eq. (16.78).

16.8

Derive the expression (16.74).