Emotional response upon first hearing harmonious polyphonic music

Judith Conrad wrote:
"...I once read a 19th century book on native american music out of my public
library. It was written by some missionary, who brought a piano out to North
Dakota or some such place. He would have the native singers sing him their
favorite songs, and then he would figure out how to 'harmonise them properly.'
So thrilled would they be by finding out thereby what their music was supposed
to sound like, he reported, that they would immediately begin to drum along.
Sometimes, they would be so transported into ecstasies by the revelation of
his piano playing, that they would drum louder and louder -- sometimes to the
point where he could no longer HEAR his piano playing!"

The response of the Indians in North Dakota upon hearing their
songs harmonized on a piano, which I suspect might have been
almost their very first exposure to polyphonic music, reminds
me of some things I read in music history books giving reports
of responses of people in Europe to developments in polyphonic music in the
middle ages and early renaissance. First there were
contemporary reports dating from about 1200 AD, at which time
three and four part sung music, as contrasted with two part
music, began to be performed by choirs of monks at the Notre
Dame church in Paris. These reports spoke of people "shuddering
in the doorways" of the church awestruck by this new fuller sounding music
which was just starting to be performed.
Then, from a later time, there were several
reports from the early 1400s speaking of the
beautiful singing of English choirs travelling on the European
continent. I believe that these English singers were effectively
using consonant 4:5:6:8 triadic harmonies, which created a
different emotional effect than did the harmonies of the late Ars Nova music
familiar to continental listeners at that time, which
I believe would have had less consonant thirds.

It seems to me that the fact that the Indians responded very
enthusiastically to the sounds of their music deepened by the
full harmonies of the piano is evidence which tends to support
the belief that although not all peoples have developed a
polyphonic music, there is something about full chordal harmony
in music which is naturally appealing to people everywhere and
which people will gladly incorporate into their music when they
have once experienced it.

On a slightly different train of thought - I've found some
arrangements for native American songs published in Mexico
in 1951. Below the title of the first arrangement for piano and
voice is the annotation: "Reduccion para canto y piano del son
anterior". Would someone on this list be able to suggest more
explicitly what is likely to have been meant by "piano del son
anterior" which I translate literally into English as "piano
having the former sound" ?

Dave Hill, La Mesa, CA