LFE, an abbreviation for Low-Frequency Effects, is commonly used in describing an audio track contained within a motion picture sound mix. The signal from this track, ranging from 10 Hz to 120 Hz, is normally sent to a subwoofer.
Later formats such as Dolby Digital retained the LFE channel, although this is more through convention and backwards compatibility than necessity, as digital formats have greater dynamic range than the magnetic analogue recordings on 70 mm prints, and modern sound processors have bass management functions to redirect bass from any channel to a subwoofer.