Choral Phonetics

Controlling Formants

I learned to adjust the first three formants independently and accurately. The independent formant control is the basis of overtone singing, a vocal technique in which a singer apparently sings two tones at the same time by tuning two resonance frequencies to one and the same frequency and then singing a “formant melody” along the harmonic series with the resulting double resonator. For choir singers it is only necessary to control the second formant, because it conveys the predominant sound impression.

The first step to control the formants is a hearing training in order to identify the harmonics. Tongue movements are trained in a second step. The second formant is regulated by the epiglottis and the root of the tongue.

When formants lie exactly on frequencies of partial tones of a singing tone, the voice sounds full and loud, the general goal in classical singing.

The IPA Vowel Chart is Too Inaccurate

Conventional IPA vowel chart. Source: Grendelkhan, Nohat (own work) (CC-BY-SA-3.0), via Wikimedia Commons.

As soon as the formants are being perceived and adjusted as pitches, the vowel descriptions of phonetics – closed/open, rear/front, rounded/unrounded – are no longer useful and far too imprecise for what choral phonetics requires.

In choral phonetics (generally in singing phonetics) it makes more sense to indicate the vowels as tone pairs/tripples of formants. Vocalists learn to control their vocal tract in such a way that they can change individual formants in pitch, completely different from phonetic descriptions, where two formants are mostly moved simultaneously and unconsciously. I will shortly be submitting a proposal for a singing vowel chart that describes the exact location of every vowel, regardless of language.

Practice Example: Amen

The following example shows how this can look like in a choir. The word Amen is sung as a four-part D major chord.

Bass brightens up the syllable “men” a little bit with every step by placing its 2nd formant on the 8th, 9th or 10th partial (harmonic).

A Perfect Third in Alto Supported by a Bright Vowel in Bass

As soon as the bass accentuates the 10th harmonic, the perfect third (third variation, bar 6), a significant change of intonation occurs in the alto voice. It drops to the natural third (14 cents below the equal tempered thirds). The 10th harmonic, F6 sharp, in the bass voice is identical to the 4th harmonic in the alto F sharp. The alto intuitively adapts its fundamental to the perfect third in order to avoid beats (assuming chamber choir qualities). The chord results in just intonation. At the same time, soprano and alto form a perfect minor third with all harmonic and thus produce D2 as a difference tone, an octave below bass. The whole chord sounds full, room-filling and stable.

The second variant (bar 4) produces a very stable fifth. With exactly the same formant arrangement (identical pronunciation) in bass, tenor and soprano, all three voices emphasize the same overtone E6, as the 9th partial in bass, 6th partial in tenor, 3rd partial in soprano.

Freedom of the 2nd Formant in the Syllable men

The syllable men is spoken with the neutral vowel schwa, ə. Depending on the fundamental tone, there are several possible timbre of the syllable in singing. Bass can sing men on D3 in such a way that either the 8th, 9th or 10th harmonic – D6, E6 or F#6 – will be amplyfied without significantly changing the vowel character.

The figure shows the formants recorded with vocal fry, i.e. voiceless. The partials of the fundamental d are drawn as lines. On the right you can see the position of the third “men” in the F1/F2 diagram.

In vocal-fry technique the 2nd formants are clearly audible as pitches. In the sung version, however, listeners without overtone training describe the difference rather as a slight brightening of the vowel. The formants are more difficult to hear with the harmonic as a sound source. Overtone-trained ears, on the other hand, clearly hear the partials and distinguish the vowel qualities just as differentiated as they distinguish the tones D, E and F#.

Minor Key Sounds Better Without 10th Harmonic

In a minor chord, on the other hand, the 10th harmonic in bass must be avoided, as otherwise the alto will not be able to keep the minor third. Minor key sounds wrong with the 10th harmonic in bass, even if all notes are sung correctly.

Special effects can be created when the 9th harmonic note (green ninth) is sung in the bass as a kind of suspended note, which relaxes into the 8th harmonic (octave) to an almost medieval calm chord.

All these effects are not consciously perceived by the listener, but they have a great influence on the impact of the music. However, in order to control these effects, the choir singers have to learn consciously to perceive the partial tone amplifications.

Easy to Learn

In practice, the whole thing quickly becomes clearer. You not only have to hear it, but also feel it physically in order to understand how choral phonetics works. It is much easier in practice than it sounds at first. The body does a lot of things on its own, because the resonance harmony is immediately expressed in relaxed singing as the ear has an archaic memory for the overtone intervals and thus for pure intonation. Both just have to be brought together first.