A loudspeaker enclosure is a purpose-engineered cabinet in which speaker drivers and associated electronic hardware, such as crossover circuits and amplifiers, are mounted. Enclosures may range in design from simple, rectanglar particle-board boxes to very complex cabinets that incorporate composite materials, internal baffles, ports and acoustic insulation.The primary role of the enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphram of an open driver interacting with sound waves generated at the front of the driver. Because the forward- and rearward-generated sound is out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced. Additionally, because they would travel different paths through the listening space, the sound waves would arrive at the listener's position at slightly different times, introducing echo and reverberation effects not part of the original sound.