From:
http://www.audyssey.com/technologies/dynamic-eq/faqDynamic EQMovie and music mixes are created at a reference level much louder than typical listening levels. Human perception of sound is different at lower playback volumes causing voices to appear brighter, bass to diminish and the surround soundstage to become less enveloping.
Audyssey Dynamic EQ™ adjusts the frequency response and surround volume levels moment-by-moment. The result is something never before possible—bass response, tonal balance and surround impression that remain constant despite changes in playback volume. This is the first technology to correctly combine information from incoming source levels with actual output sound levels, a pre-requisite for delivering a loudness correction solution.
Why can’t I hear my surround sound and bass when I turn my volume down?The scientific reason? It's so you can sleep at night. If we could hear low frequencies at the same levels as the higher frequencies, our heart and other vital organs, which produce a lot of noise at low frequencies, would keep us awake. But evolution wasn’t aware that one day we'd want to watch movies the way they were created. When designers mix sound for movies they listen at very high levels. The decisions they make about the balance of frequencies and the level of surround sound is done for the loud volumes in movie theaters. When we listen at home the sound is a lot quieter, and so our balance is completely different. That's why movies sound like they're lacking bass and surround. Dynamic EQ is designed to fix that. It restores the proper balance by making adjustments for human perception at lower listening levels.
What are the best Dynamic EQ settings for movies, music, and video games?Movies are mixed in rooms calibrated for film reference. To achieve the same reference level in a home theater system each speaker level must be adjusted so that –30 dBFS band-limited (500 Hz – 2000 Hz) pink noise produces 75 dB sound pressure level at the listening position. A home theater system automatically calibrated by Audyssey MultEQ will play at reference level when the master volume control is set to the 0 dB position. At that level you can hear the mix at the same level the mixers heard it.
Audyssey Dynamic EQ is referenced to the standard film mix level. It makes adjustments to maintain the reference response and surround envelopment when the volume is turned down from 0 dB. However, film reference level is not always used in music or other non-film content. The Dynamic EQ Reference Level Offset provides three offsets from the film level reference (5 dB, 10 dB, and 15 dB) that can be selected when the mix level of the content is not within the standard.
0 dB (Film Ref): This is the default setting and should be used when listening to movies.
15 dB: Select this setting for pop/rock music or other program material that is mixed at very high listening levels and has a compressed dynamic range.
10 dB: Select this setting for jazz or other music that has a wider dynamic range. This setting should also be selected for TV content as that is usually mixed at 10 dB below film reference.
5 dB: Select this setting for content that has a very wide dynamic range like classical music.
