Unfortunately, it's hard to convey this effect with a recording—it's much stronger if you're producing it. So I guess I'm mostly talking to other vocalists.
The first key bit seems to be that voices can sing in just intonation, i.e. whole number ratios:
Conversation
(I'm totally skipping explanation of overtones, temperament, and the harmonic series here… for a wonderful intro, see 's youtube.com/watch?v=i_0DXx)
1
8
In four-part harmony, singing the harmonic series 1, 3, 4, 5 can produce one form of this effect: i.e. the tonic, and its major triad in second inversion an above.
e.g. this (remarkable) cadence resolves to that disposition in A major (A E A C#): youtu.be/Qo_N9_ZFBhs?t= Tingly!
1
8
I think it feels tingly because of all the overtone interactions between those whole numbers. The bass's overtones reinforce all the other fundamentals; then there'll be strong overlaps at 12, 15, 20, etc.
1
5
In my experience, this effect is much stronger when singing with less vibrato and quite a bright timbre (i.e. more upper overtones!). I hadn't really understood this—I sing mostly contemporary pop—but barbershop stylistic choices are mostly in pursuit of this effect.
2
9
They lean heavily on dominant sevenths, which (tuned in just temperament) are the 4, 5, 6, and 7th harmonics of a root two octaves down. en.wikipedia.org/wiki/Harmonic_ Lots of interesting overtone interactions create an angelic "fifth voice" singing high above! "Ringing chords".
1
5
How do inversions/dispositions influence the effect?
eg If the Notre Dame cadence resolved to root triad instead of second inv above bass: 1, 2, 5/2, 3 instead of 1, 3, 4, 5. That'd emphasize a root-fifth interaction, which might detract from the sus resolution of the third.
1
3
I experience something like this effect with close dissonant chords, too, which barbershop eschews. What's going on there?
e.g. in Eric Whitacre's music, there are lots of so-called "fist chords". These sometimes produce the effect for me too! Why? Overtones aren't very aligned.
3
4
When you started describing this familiar effect I thought of Whitacre immediately, and was glad to see you mention his work. Have experienced it playing instrumental arrangements of his, and as an audience member, though as you noted you feel it more as a member of the ensemble.
1
1
I think there is something to the idea that you feel it more acutely if you are contributing to it, but I also wonder if it's a matter of being amidst the ensemble. If you're lucky enough to sit inside a drum and bugle corps horn arc when they're on, you can really feel it.
1
1
Replying to
Yeah, if I’m standing in a circle with a few other vocalists working out part of the arrangement without me, I can sort of feel it—though still not as strong!