Singing in tune
There are at least three ways for a singer (or instrumentalist) to tell if their intonation is correct.
A system used by many singers, in lieu of any other, is to estimate the width of the interval between their current note and note about to be sung, and then to change pitch according to their sense of what this interval sounds or feels like.
This turns out to be the least reliable system. The slightest underestimation or overestimation of the ‘width’ of the interval, especially if this inaccuracy is compounded over the next series of intervals, will lead sooner or later to the singer being noticeably out of tune with the accompaniment.1 This system is too relative. Errors creep in one after another after another.
A more absolute system is to always sing into the currently sounding chord. There is always a chord happening in the accompaniment. Sometimes it is very apparent, sometimes it is more disguised, but if the singer can become aware of the presence of that chord, she can dissolve her tone into that chord and thus be perfectly in tune with the chord.2 In more modern pieces there are still chords, except that the chords are more dissonant. None the less, they are present.
The third way of singing in tune is the most reliable. It is to maintain an overall sense of the key of the piece which would thereby include all the notes in that key.
This is harder at first to cultivate. Here is how I go about it. I create a simultaneous cluster made out of all the notes in the scale of the key. Usually I create an eighth note cluster, one octave from the tonic to the next higher tonic. For example, if the key is C Major, and I’m working with a soprano (or the soprano section of a chorus), I play the eight note cluster c-d-e-f-g-a-b-c (from middle C to the octave above middle C). If I were working with a bass or choral bass section, I would do the same cluster one octave down.
Continuing with the example of C Major. I play the cluster, and hold it, and invite the singer(s) to sing just the tonic note in that cluster (middle-c if a soprano). I then replay the cluster and ask them to fine-tune their pitch until it dissolves into the cluster, I.E. it reaches a point where they cannot distinguish their voice from the sound of the cluster. To hear their voice separately from the cluster is to be out of tune with the scale.
I repeat this procedure for each ascending note of the scale. Though the singer is changing from one scale note to the next, the cluster in no way changes sound.
I have used the word dissolve a couple of times. Here is a general explanation of the principle involved.
An example. A clarinet and a bassoon have different tone qualities – until they sound the same note. When they are in unison on the same pitch we hear only a single tone quality, one different from the clarinet’s and different from the bassoon’s. The sound is more as if coming from just one instrument; we could name the instrument the ‘clarinet-bassoon’. The same goes for a clarinet and a flute playing in octaves, or a bassoon and a French horn playing in unison. There are many other such combinations among the instruments of the orchestra. In a similar manner, the goal for the singer is to have their note blend in so completely with the sounds around it that one hears something new tone-quality-wise (for instance a the ‘soprano-piano‘ instrument).3
Here is an exercise I use to achieve this blending of voice with accompaniment.
The singer holds a single note, starting quite softly; softly enough that her sound dissolves into the sound of the other instrument(s). Next, in a very controlled manner, the singer gradually increases the loudness of their note, but at all times with the goal of still feeling that their sound has dissolved in the general pool of sounds. Even at its loudest, the note should be so clearly mixed in with the accompanying sounds that the singer remains almost unaware of the separateness of their own sound.4
When working with a chorus, I use the same technique: every individual singer dissolves their voice into the pool of sound created by all their section members en masse. Sometimes I will ‘build this up’ by starting with just one singer, adding a second, adding a third, etc. The goal is to remain a single sound, with no hint (even with different rates and widths of vibrato) to suggest there is more than one singer. The result is a surprisingly pure and rich sound!
1 Let me give you an exaggerated example. In acoustics, each semitone (for instance C to C-sharp) is divided into 100 smaller units or “cents”. Consider a person singing a chromatic scale upwards starting on middle C. To get to the exact pitch of the C#, the interval between the C and the C-sharp must be 100 cents. If it is five cents short (95 cents), the pitch of the C# is going to sound fairly correct (it is off by 5 percent of a semitone). But let’s see what happens if they continue singing half steps that are just 95 cents wide. The C is in tune. The C# is five cents flat. The D is ten cents flat. The D# is fifteen cents flat. A difference in fifteen cents is very noticeable to the average listener’s ear. If they go on to E and then F, the “F” will be 25 cents flat and by the end of an octave the final “C” will be twelve times five, or sixty cents flat. Ten cents more than a quarter tone.
2 If the chord is tonal, then it is helpful for the singer to know whether the note they are singing is the root note, the third, the fifth (or the seventh) of the chord. If none of these is the case, then the singer should be finely aware of the exact out of tune-ness of their note relative to the nearest note in the accompaniment.
3 A timbre that is that neither one nor the other but the combination of the two.
4 From the pianist’s point of view, it is often the case that they are trying to sound less like a piano and more like a human voice (singing legato).