The Low Frequency Effects channel, or LFE, is a source of some confusion in surround sound. The LFE channel was originally developed to carry extremely low "sub-bass" cinematic sound effects (e.g., the loud rumble of thunder or explosions) on their own channel. When loud sub-bass effects are on a different channel, this allows theaters to control the volume of the sub-bass effects, so that it suits the size of their sound reproduction system and the acoustic environment of their cinema. Independent control of the sub-bass effects also reduced the problem of intermodulation distortion in analog movie sound reproduction.
In the original movie theater implementation, the LFE was a separate channel fed to one or more subwoofers. However, home replay systems may not have a separate subwoofer that is able to handle the sub-bass effects. As a result, modern home surround decoders and systems often include a bass management system that allows bass on any channel (main or LFE) to be fed only to the loudspeakers that can handle low-frequency signals. The salient point here is that the LFE channel is not the "subwoofer channel"; there may not even be a subwoofer and, if there is, it may be handling a good deal more than effects.
Some record labels such as Telarc and Chesky have argued that LFE channels are not needed in a modern digital multichannel entertainment system. They argue that all available channels have a full frequency range and, as such, there is no need for an LFE in surround music production, because all the frequencies are available in all the main channels. These labels sometimes use the LFE channel to carry a height channel, underlining its redundancy for its original purpose.
LFE is sometimes expanded as Low-frequency Enhancement.
