Here we go off topic:

The Dufay motet is Nuper rosarum flores, and uses many 3:4:5 proportions
which Brunelleschi used in the dome as well. I looked for literature about
just this several years ago, and found nothing to suggest that Dufay
explicitly intended the ratios and canons to produce an environment specific
effect. If you have a source, I'd love to know it! I may have been also
looking in the wrong places, but there's also little concrete evidence that
Dufay's motet was ever performed in Florence either. 

Grant.

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Dufay wrote a piece specifically to be performed in Brunellesci's dome
where the  tempo of the music was such that a reverberating phrase
returning from the walls of that space formed a canon with the next