These days I am in Turin singing with a choir; on Thursday and Friday we will be performing Mahler's Second Symphony with the RAI Symphony Orchestra. The choir in question is called Coro Maghini and is conducted by
M° Chiavazza, a conductor with polyphonic training, one of those who pays extremely close attention to the choir's intonation.
I therefore wanted to take this opportunity (and the free time I have these days) to introduce this topic, which is little known but very important (and very "fashionable"). It is a vast subject, so I will try one of a thousand possible approaches. If you are interested, I will delve deeper over time.
A series of in-tune people do not necessarily form an in-tune choir.
What is an in-tune choir? It is a choir that performs, above all, in-tune chords (or harmonic overlaps). And what, in choral practice, is an in-tune chord? It is a chord whose degree of consonance is as high as possible.
What I have written may seem trivial or it may seem inconceivable. Trivial, because I have spoken about nothing. Inconceivable, because I introduced the topic of consonance as if it were the sole element of harmonic theory. In reality, it is not, but it is the most important element of a choir's intonation.
Consonance is not just a concept of musical theory; it is above all a concept of acoustic physics. I have learned to define it as the quality of a harmonic overlap expressible with a fraction of integers, where the lower these numbers are, the higher the degree (of consonance). In simple terms, the highest possible consonance is a unison, which is expressed by the number 1. The second most consonant harmonic overlap is the octave. Two voices singing an octave apart form a harmonic overlap expressible with the fraction 2/1. These are two very low integers, the lowest possible after 1. Going on like this, we can express the entire series of intervals (semitone, tone, minor third, major third, etc.) with fractions. And we will arrive at an intonation prospect very similar to the famous natural Pythagorean system.
Taken this way, the issue seems merely mathematical. In reality, the practical consequences are gigantic.
Let's take two choirs. One sings a hollow fifth, like C-G, and sings it by tuning perfectly to the perfect fifth 3/2. The other choir, however, does not make a perfect just fifth, but muddies the intonation a bit and sings, I don't know, a fifth of 300/197. What difference will you hear? Probably none :-) furthermore, it is very likely that the "out-of-tune" choir will appear richer, more complex to you, and this is because when we speak in abstract terms of intonation, we are referring almost to MIDI files, to sine waves, i.e., to sound sources that emit A SINGLE FREQUENCY. The voice does not emit a single frequency; it is a mess of different things, therefore a chord will never be perfectly perfect.
However, when the difference between the two choirs becomes more significant, then first of all one thing happens: the out-of-tune choir sings more quietly.
The first and least considered consequence of in-tune polyphony is VOLUME. Because two consonant notes correspond to two consonant waves, and when two waves are consonant, they come into phase and into RESONANCE. That is, they amplify each other.
This mechanism is not new to musical knowledge. In reality, it is one of the best-known vocal mechanisms of all time. When the chest C was not yet known, nor the "lyrical" emission technique and all the other things discussed in opera houses, European cathedrals were built to amplify perfectly tuned perfect triads that were incredibly resonant. I have sung in churches, even with quite large choirs, and I assure you that it is tremendously difficult to make yourself heard. Everything reverberates and everything sounds terrible. Then a little English choir of 20 people comes along and brings the walls down... this is possible precisely because ancient music IS WRITTEN to be insanely in-tune.
I will stop here for now. Tell me if the topic interests you ;-)
