But what exactly do these channel numbers mean? A two-channel system consists of a stereo with two speakers on the left and right, while a three-channel system adds an additional speaker to this two-channel setup for crisper audio output. 3.1–channel setups feature an additional subwoofer (the .1 channel) for low frequency sounds, while 5.1-channel systems add rear speakers to deliver enhanced sound that extends behind viewers. The 5.1.4–channel setup seen in soundbars includes two additional height channel speakers that produce three-dimensional surround sound to deliver the sound of objects moving off-screen.