Simplified Explanation(Scroll down a bit, and download the comparison MP3's)

Taken from above link:

For centuries we have been playing musical instruments that are out of tune...
Ever since the emergence of polyphonic instruments, including all keyboards as well as fretted instruments such as the lute and guitar, tuning has always been a compromise. Several attempts from the 16th-18th centuries to standardise the temperament (tuning) of church organs and virginals helped a little, but they were battling against the mighty laws of physics.

First suggested in 1636, our modern “Equal Temperament” was only in common use from the late 18th century onwards because it was considered much too much of a compromise at the time. Despite it’s one advantage (the freedom to play in any key), Equal Temperament simply dilutes the fundamental problem, spreading it across all the notes in the octave.
Experienced singers and string players use “just” intonation – they adapt to any keys and modulations (key changes) because they have infinitely variable control over pitch. Within certain limits, the pitch of wind instruments can also be varied by adjusting embouchure (lip position/tension). A group of musicians instinctively approaches a common overtone structure, minimizing the “friction” between all the voices in a chord. This results in the wonderfully rich but compact sound of symphony orchestras or gospel choirs.

Unfortunately, real time intonation was not a feasible proposition for makers of keyboard instrument. Finding a usable method of performing fine adjustments to each and every note seemed physically impossible, especially when playing polyphonically.
These days, digital musical instruments can automate this process. The Pure Tuning (aka. Hermode) algorithm analyses chords and immediately adjusts the pitch of each note so that the prominent harmonics line up. Especially for normal synthesizer sounds, the difference between Equal Temperament and Pure Tuning may appear to be rather subtle at first (though this difference can be accentuated – see below):
Select the factory preset C126 (-Init-) on your Virus. Turn the Detune value down to 7 to make the phasing between the two oscillators nice and slow. Play a few simple major chords, or just a C-major triad if you prefer, and vary the PureTuning Intensity parameter.

At 127, PureTuning is fully on: The chord is well intonated (like a choir) and does not exhibit any beating between notes. This may seem a little unusual at first, but it sounds perfectly “straight” and correct after you have familiarized yourself with the effect. Setting PureTuning back to zero (“Equal”) switches it off again: The chord is beating and, after comparing the two extremes, this original setting sound equally unusual. The chord now appears to be tuned rather oddly, not quite pure enough, slightly spoiled compared with the maximum setting.
Astonishingly, this is the very same Equal Temperament we have been hearing all our lives...

Long Detailed Explanation(Check out "Historical" Section for explanation, and "Examples" for classical examples)

___________________

quote:

Originally posted by dj_alfi change your avatar for fucks sake.