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Low-frequency effect
From Wikipedia, the free encyclopedia
Low-Frequency Effects (LFE) is the name of an audio track specifically intended for deep sounds ranging from 10-120 Hz. This track is normally sent to a subwoofer, known as the Low Frequency Emitter.
The LFE channel originated in Dolby Stereo 70 mm Six Track film prints, as a way of providing louder bass and sub-bass effects, without detracting from the quality of the standard audio channels. The LFE channel is conventionally played back 10 dB louder than the main channels, giving significantly more recording headroom. Also, the separate recording allowed straightforward installation of extra dedicated subwoofers, removing the need to upgrade the main speakers, or install an extra LFE Crossover.
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 (LFE Crossover).
