In my personal opinion the Portable Soundfield System is the most cost effective and acoustically efficient classroom amplification system available today. Custom designed systems can be great and if every classroom in the school is going to have a soundfield system then this is a great way to go but if only a few classrooms are going to be equipped, ether for student or teacher accommodation use, then the portable system that can change rooms either during the school year if needed or for the following school year as students and teacher move classrooms will provide more benefit for the money involved. The unit shown to the left is an infrared (IR) system that uses an invisible beam of light between the transmitter and speaker. This provides great sound quality and since the sight beam is blocked by walls there is no channel management to worry about between classrooms. The disadvantage to the IR system is it can not be used outdoors as the sun is the biggest infrared emitter in the neighborhood and causes just static to be heard from the speaker so IR is an indoor unit only.