For those not familiar with the term LFE (Low Frequency Effects): The .1 channel is the LFE or sub-woofer channel. It can also be present for stereo programs. Low Frequency Effects track. The .1 channel of a Dolby Digital, DTS, or SDDS soundtrack. The LFE is strictly low-frequency information (20 to 120 Hz, with 115 dB of dynamic range) that's added to the soundtrack for extra effect. This track does not inherently contain all the bass of the soundtrack.
Sound Format Codes
DTS 5.1 (DTS-encoded DVDs offer better sound than those with Dolby Digital)
DTS Neo6 6.1/7.1 (multi full-band channels of matrix decoding from stereo matrix material)
DTS ES 7.1 (ES adds up to two rear center-surround channels to the standard 5.1 array and delivers more enveloping surround)
DTS 96/24 5.1 (superior quality but doesn't require a special player; six discrete channels; full video capability)
SDDS Sony Dynamic Digital Sound 7.1 channel
Dolby Digital 5.1 5.1 channels AC-3 encoded
Dolby Digital 2.0 2 channels AC-3 encoded
Dolby Digital 2.1 2.1 channels AC-3 encoded
Dolby Digital 4.0 4 channels AC-3 encoded
Dolby Digital 4.1 4.1 channels AC-3 encoded
Dolby Digital 1.0 mono AC-3 encoded
Dolby Digital may sometimes be short-handed as DD
PCM uncompressed digital sound
MPEG-1 2 channels MPEG encoded
MPEG-2 7.1 channels MPEG encoded