ABSTRACT
When a loudspeaker is close to a room boundary, the boundary has an effect on the sound radiated into the room. When a loudspeaker is mounted on or in a wall, there are effects, and if there are open cavities close to the loudspeaker, they too influence the radiated sound. In rooms there are multiple boundaries, some adjacent to and none very far away from the loudspeaker, each contributing something to variations in frequency response at listening locations. The adjacent-boundary effect changes the acoustical radiation resistance experienced by the loudspeaker, and as a result the sound power radiated by the loudspeaker at different frequencies is altered. Having expounded on the problems created by adjacent-boundary effects, it was no surprise that Allison proposed a loudspeaker design that minimized the effects. The Acoustic Research AR-9 incorporated some of Allison's adjacent-boundary compensation ideas. To avoid adjacent-boundary problems, loudspeaker drivers must be less than half a wavelength separation from large reflecting surfaces.
