THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

12.16 Acoustic Barriers 311Figure 12.16. Schematic of a room with a barrier in position. Region 1 and region 2 areseparated by a plane defined by ABB ′ A ′ .where the first term on the right of Equation (12.50) is the mean-square pressureat the receiver due to the reverberant field and the second term represents themean-square pressure due to the diffracted field around the edges of the barrier.Recognizing that L p2 = 10 log(p2 2/p2 ref), we can express the sound pressure levelL p2 at the receiver in terms of the reverberant and diffracted fields:( p2L p2 = 10 log r2+ pb22p 2 ref). (12.51)The barrier insertion loss IL is given in terms of SPL by( p2)IL = L p0 − L p2 = 10 log 0. (12.52)For the room of Figure 12.16, we shall assume an equilibrium condition and thatthe area of the barrier is considerably smaller than the planar cross section of theroom, i.e.LH ≫ L b h. (12.53)p 2 2