The LFE channel was created to handle blockbuster bass beyond 40 Hz.

Evidence

Individual channels in the original film soundtracks are broadband, but the main cinema loudspeakers operate usefully only down to about 40 Hz. This was adequate until the first “blockbuster” films needed more low bass. Existing cinema systems were unable to handle the load without distortion and they lacked genuine low frequencies, so a new channel was created, called either “low-frequency enhancement” or “low-frequency effects” but always LFE. The bandwidth was restricted to frequencies below 120 Hz and the signal level was reduced by 10 dB on the soundtrack to allow for more headroom, which was a problem with analog soundtracks of the day. The 10 dB is restored on playback. — Toole, Floyd E, Sound reproduction- the acoustics and…, 771

Categorization

• DEFINE: Explains the meaning and origin of ‘LFE’ (low-frequency enhancement/effects), clarifying why there is a separate subwoofer channel and its 40-120 Hz bandwith plus 10 dB headroom offset.