Surround channels are audio channels in surround sound multichannel audio. They primarily serve to deliver ambience and diffuse sounds in a movie or music soundtrack. Unlike most typical speaker placements, surround speakers are often intended to radiate such that the sound reflects off walls so that the sound arrives at the listening position indirectly as a reflection rather than a direct wave. Often dipole (sometimes even quadpole) speakers are used to do this, especially in small or home theater applications where an array of surround speakers as in a movie theater is not practical or possible.