ABSTRACT
Figure 6.1(a) shows nine 7-m-long, 0.2-m-high parallel walls constructed from 594 standard house bricks on an asphalt-covered car park area at
the Open University, Milton Keynes, United Kingdom. Each wall in this arrangement contains 2 rows of 33 bricks, 0.064 m wide. The edge-to-edge spacing between the walls is 0.25 m giving a total array width of 2.57 m. The bricks have been rearranged also to form a “staggered grid” pattern (Figure 6.1(b)). Both the parallel wall and staggered grid arrangements occupy a total area of about 18 m2. The location of the car park, about 140 m from a busy main road (Figure 6.1(c)), made it possible to use two microphones to measure the trafc noise levels before and after erecting the walls. The microphone most distant from the road was located either 0.5 m or 1 m from the nearest wall and at heights of either 0.1 m or 0.3 m. The microphone on the road side was 0.5 m from the nearest wall and 0.1 m above the ground.
