If you place loose sand on a flat surface and then blast sound at a certain pitch, the sound waves will cause the sand to move into a formation. Different pitches yield different sound wave patterns, and each pattern is always produced with a specific pitch.
I went in the Chapel maybe 2 months ago and you wouldn't believe how fascinating this Chapel is. I thought it would only be a place glorified by the novel but no ... You can really find some wacky and intriguing stuff there, such as stones depicting cereals which were discovered in America 50 years after the Chapel was built. And that's far from being the only weird stuff there. Stitch216 may add something to this (coming from Edinburgh ...)
The only vaguely factual bit I think relates, if I remember something I once read correctly, to when St. Ambrose arranged the modes and the scales were generally accepted as running upwards (i.e. increasing in pitch) as the previous model of having them running downwards was seen as 'ungodly'.
Link which appears to have some relevant information in it for anyone interested here.