 For cost and practical reasons the most common setup is satellite speakers, typically bookshelf speakers for the side, back, and sometimes the front and center channels, rather than larger speakers for each channel.Finally, most home theater and many musical home audio applications, began in the late 1990s to incorporate separately-enclosed subwoofers to handle deep bass.Human perception of low-frequency sound is relatively non-directional, so a single subwoofer cabinet placed anywhere in the room (even hidden behind a sofa) is usually sufficient and may be placed anywhere.