In talking to many people about temperament, many people including musicians think that it's a "high faluting" subject and that they would not be able to hear the difference.
What temperament is really about is that if you go up 7 octaves (from memory - I'm bound to get this wrong!) and if you go up 12 fifths, you arrive on the same note. Well you do on the piano . . . But you don't really if you tune your octaves properly and your fifths properly too. An octave note above another is a doubling of frequency. An interval of a fifth is one and a half times. So 2x2x2x2x2x2x2 = 128 and 1.5x1.5x1.5x1.5x1.5x1.5x1.5x1.5x1.5x1.5x1.5x1.5x = 129.7 - so this means that the two notes are very near but not the same. In order to make them the same on the piano we narrow the fifths a bit and at the top we stretch the octaves . . . And the result is far from being in tune.
In equal temperament, we squash the fifths equally. In Unequal Temperament we squash the fifths unequally and this resulted in each key having a different character.
Bach wrote his famous "48" not for the Equal Tempered Clavier but for the Well Tempered Clavier - a system where, unlike just tuning in which only one or two keys can be played comfortably, all the keys can be played happily - a system of equal temperament where some keys are more equal than others! Even some current music teachers continue to peddle the myth that Bach was composing for equal temperament. In addition, on the manuscript Bach drew a famous "squiggle", the loops of which can possibly give clues as to tuning. An American, Bradley Lehman, caused a lot of controversy turning the squiggle upside down to interpret whilst others have interpreted it the right way up. The result is that Lehman's resulting tuning achieves maximum deviation in keys of three accidentals, whilst others accord broadly with historical precedent - Kirnbirger and in the 1960s Kellner in the same spirit, bringing greatest piquancy to the remotest keys, which makes a lot of sense.
This whole issue is relevant to piano music http://www.youtube.com/watch?v=41xRupc3Hz8
and really opens one's earshttp://www.youtube.com/watch?v=YXzSXWaQGmA
and is one component of the very striking soundhttp://www.youtube.com/watch?v=wSf7-4t_SWc
beyond mere voicing and tonal construction of a pipe organ
Meantone tuning gives 8 perfect thirds, reeds like a proper brass band playing on harmonicshttp://www.youtube.com/watch?v=E8m2ok1Hlh0
and tierces sweethttp://www.youtube.com/watch?v=C16HE2uw3_U
where they do not achieve the same effect on an equal tempered instrument trying to achieve the French soundhttp://www.youtube.com/watch?v=HAql0dfZQHY
merely sounding reedy rather than sweet.
It's actually in doing such experiments that I believe that electronics can be the CAD for pipe organs. Just as computers are so necessary in predicting in architecture how buildings will fit together, or in how a drug will behave or indeed what the weather will be like tomorrow, electronics should be more appreciated as a research tool:
I should add that many of the recordings above were made "off the cuff" with camera microphone and automatic volume control rather than with a seperate CD quality soundtrack and therefore are not representative of the proper sound of the experimental instrument in use. Some people listen to YouTube recordings through plastic speakers and then say that an instrument sounds plastic!
I hope that the examples above might inspire others to flirt with temperaments and see what can be performed and what repertoire is excluded by their use. Merely being "out of tune" is not necessarily "wrong" - it is simply that our ears are unaccustomed to some tonalities and that they really bring a refreshing change! I like the Bach Dorian Fugue in meantone and Couperin and other French Baroque composers deliberately sailed into "crisis points" which became lacking in comfortable equal temperament leading "modern composers" into foully ostentatious discords to get their effect . . .