In the surround systemsDolby Digital, Digital Theatre Sound( DTS), Sony Dynamic Digital Sound( SDDS) and MPEG Sur round, low frequencies are transmitted to the woofer or subwoofer of the loudspeaker system via a special low- frequency channel with a greatly reduced bandwidth. In Dolby Digital, the acronym LFE stands for Low Frequency Effect, in Digital Theatre Sound (DTS) for Low Frequency Enhancement.
The bandwidth of the LFE channel is limited to the basses and thus to frequencies between 20 Hz and about 100 Hz. The LFE channel is separate from the other speaker channels and its amplitude can be controlled with Bass Peak Management. This avoids overdriving the subwoofer and possible low-frequency effects are amplified or attenuated.
Since the low frequency channel has only a limited bandwidth, it is not counted as a full audio channel in the nomenclature of surround systems, but is added to the channel specification after the dot. As the 5.1 example shows, this system has 5 full channels and one LFE channel.