LFE (low-frequency effects)

The channel is band-limited, normally to 120 Hz, hence its billing as a tenth of a channel. It plays back with +10 dB of extra gain relative to the main channels, giving the film mixer plenty of room for truly heavy effects without the rest of the mix having to step aside. The idea goes back to 70 mm film in the 1970s and came along when Dolby Digital made 5.1 the norm in the 1990s.

LFE is not the same as the subwoofer output. Bass management in the receiver also routes low bass from the regular channels to the sub, and the LFE channel may be discarded entirely in a stereo downmix. A mix that puts important bass only there risks sounding thin on headphones.