Whenever I talk of unequal temperaments the response is that they are fine in the good keys and that one needs to change temperaments for those in "bad" keys in which other temperaments might be better. The thought that temperaments were used only to create greater harmonicity is a common misperception.
Unequal temperaments also created various forms of discomfort and harmonic emptiness, hollowness - absense of harmonic associations and harmonic meanings, all of which were intended emotionally and sometimes for special effects.
on the piano further to http://www.youtube.com/watch?v=XmCgZq6Lmm0
in which I explored audible products of hearing two tones together on the harmonic series, I showed how Chopin used the unequal temperament effects in his famous Funeral March.
The psychoacoustic effects of harmonic accordance are extraordinary. Looking at the wave peaks that pass the ears in a given time, | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | heard with
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adds to produce
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| | | | | | | | | | | | | | | | | | | | |heard with
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adds to produce
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which is either heard directly or "understood" in the brain. The combined coincidences of wavefronts make this pair of notes, especially when played with other relating notes, all adding up, all confirming the periodic peaks, make this sound "solid".
The ear and brain identifies a non-according pair of notes differently:
| | | | | | | | | | | | | | | | | | | | | is heard with a detuned note
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(the exact peaks should be equally spaced but typographical limitations do not allow this
) the wave peaks don't coincide in a way that relates to any harmonically related note. In fact there is only one point of coincidence in this series: |
and therefore the notes within any surrounding chord do not have the same auditory meaning. The wave peaks don't coincide in any way or pattern that the brain can anchor onto any other surrounding note, and so the two notes, and other any notes with them sound hollow, meaningless, or simply confuse any other accordance that there might be. Equal temperament does this all the time - the "certainties" that the brain understands and recognises in perfectly harmonic chords are missing and in the unequal temperaments even more so in the black keys. There are times when pianistic composers arpeggiate in the remote keys, skating around with fragility as on thin ice. Here's an example of Liszt in B major: http://www.youtube.com/watch?v=g6QT3e-Mqh0
and again, Liszt setting up a landscape: http://www.youtube.com/watch?v=Ov-8Dc0ireI
The following piece by Couperin is really interesting. In equal tuning, it's bland although a discord or two shows up. It's easy to play so worth playing, even if classical music isn't your thing - it's worth giving a go.
Try it in Meantone if you can, and use a basic Bourdon at 8ft and 16ft pitches, soft Diapasons at 8ft and 16ft (leave them out if you only have hard Diaps), a principal 4ft a flutish 2ft and as many high sparkling mixtures as your organ has, all coupled together. (If you have access to a Hauptwerk simulation of St Maximin use - Resonnance Petit Fourniture IV, Cymbale IV Grande Fourniture II Prestant 4' Montre 8' and 16' and Bourdons to thicken it if you want, Positif Cymbale III Doublette 2 Montre 8 Prestant 4' and Fourniture III, both Positif and Resonnance coupled to Grand Orgue http://www.youtube.com/watch?v=yFTStijofmw
for actual sound - although Couperin would have expected Meantone tuning rather than the beautifully mild well temperament in use at St Maximin).
In this piece, when all the chords have notes which accord harmonically, with perfect thirds and nice fifths, the sound is BRILLIANT. These sections contrast with areas where the notes discord and the temperament enhances the discomfort. It is intended to do that, and the meantone temperament is hideously unforgiving of mistakes: http://www.organmatters.co.uk/couperinkyrie.jpg
As you go through this in Meantone, some chords are soothingly pure and express beautiful love - perhaps linger a shade on those chords which are wonderfully harmonious, and then sometimes but most noticeably in the 4th stave, second bar, first chord is excruciating crisis - Couperin goes from harmony to crisis and then resolves it. When playing this in Meantone, beyond playing the notes, I prefer to linger on those chords which have more meaning and don't simply rush through them. You can see the mark annotated after that chord to take a breath - the chord is hot so a breath is needed before we cool it down.http://www.youtube.com/watch?v=oj6mqEiSwr8
is a nice interpretation.