http://forums.dealmac.com/read.php?4,2611622
"Apple says it is similar to a loudness control:
[www.apple.com]
"If you select the "Sound Enhancer" checkbox, iTunes "enhances" the sound of your audio files by increasing the treble and bass response, depending on how you set the slider. Think of it kind of like the "Loudness" button found on an old home stereo system, but adjustable. If you move the slider toward the "high" end, iTunes boosts more of the equalization, meaning things will generally sound punchier and crisper. If you move it towards the "low" end, iTunes will decrease the same frequencies."
Others claim that there's more to it than that:
[en.wikipedia.org]
"iTunes includes sound processing features, namely an equalizing section, and its "sound enhancer", which in some languages is translated into "sound improver". The enhancer works by inserting out-of-phase components of the signal into the opposite stereo channel, a technique often used on elements in music production."
[www.logicprohelp.com]
(blueintheface):
"What iTunes does in this respect is the same as the 'Wide' button found on ghetto blasters in days of yore - some high frequencies from each channel are phase-inverted and fed to the opposite channel. This makes the stereo-width apparently greater - but comes at the expense of any real definition of placement. It might be instantly appealing in its queasy-making phasey-ness, but in reality the whole stereo image is smeared. It's an effect that destroys any spatial naturalism to any recording, and so wouldn't be suitable for use on any 'realistic' recordings say of an orchestra or a jazz band. I'm not saying it doesn't have its place - because someone will probably have a hit with the most artifically widend track next week - just to be aware of what you're doing, and sometimes what is instantly appealing ends up ultimately fatiguing. "
Some say it is a close relative of Arboretum's Realizer that combines:
[www.arboretum.com]
"Bass Maximizer * The same effect found in Hyperprism offers an incredible assortment of bass enhancement and maximization effects, ranging from subtle bass enhancement to extreme bass generation. Increase the perceived amount of bass, even on low end systems with poor bass frequency response, by harmonics which fool the brain into hearing lower frequencies.
"Harmonic Exciter * Have you ever had an audio track that sounded dull and boring, which no amount of EQ could fix? Instead of simply boosting frequencies already present, as occurs withEQ, the Harmonic Exciter generates new high frequency harmonics, thereby extending the bandwidth and increasing the liveliness of the original audio.
"Stereo Enhancement * Expands the stereo spectrum.""
