the listening area due to the figure-of-eight polar response. This means that for a given output loudness, locations falling within the "dead-zone" of the speaker do not perceive as loud a sound as they would with more traditional enclosures. Dipole speakers are said to be better for rear speakers in surround-sound systems, although this is disputed (or at least success depends on factors such as room acoustics, type of music, and so on). The THX standard specifies dipoles for the surround speakers in home theater, but that part of the spec is often ignored in practice. Disadvantages However, these enclosures are less efficient because, for the same driver, a dipole results in less sound pressure level than a closed or ported enclosure, and certainly far less than a properly designed horn. This means that the drivers mounted on a dipole enclosure must have large maximum excursions, large square areas, or both. One solution to these problems is to cross over to a closed or ported enclosure that handles the low frequencies. Another solution is to construct the dipole by means of a bipole with signal processing controlling the polar pattern. This enables switching between different polar patterns or varying the polar pattern and efficiency versus frequency and versus output level. References http://www.forsman.no/cms/ http://www.linkwitzlab.com/x-models.htm#B http://www.linkwitzlab.com/frontiers.htm#L https://web.archive.org/web/20110718144913/http://www.avreview.co.uk/news/article/mps/UAN/147/V/2/ Dipoles, bipoles and quadpoles http://www.daudio.nl https://www.soundmaxpro.com/best-bipolar-speakers/ Loudspeaker technology