The Singer’s Formant
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The Singer’s Formant
by J Marchand Knight
Timbre Lingo | Timbre and Orchestration Writings
The singer’s formant is a feature that can be observed in classical singer’s vocal quality when aiming to sing acoustically through a whole orchestra. It is described by a peak at around 3000 Hz in the spectral envelope of the singer’s voice, created through an active modification in the vocal tract resonance (an ability which can be acquired through years of vocal training). Because of the singer’s formant, spectral energy is distributed differently for operatic voices than it is for orchestras. This prevents the orchestra from masking the classical singer’s voice even through very loud sections (the voice is said to ‘cut’ through the orchestra, without having to increase air pressure and create strain on the vocal folds).
Have you ever wondered how opera singers sing so loudly? In the voice studio, operatic singing is not actually thought of as loud but rather as possessing resonance (in singers’ terms, not acousticians’ terms), focus (sometimes visualized as a laser point), cut (a non-technical term meaning the voice can cut through the texture of an orchestra), or squillo (an Italian word for the buzzy quality in an operatic voice). A classically trained voice can be heard despite being accompanied by strings, percussion, woodwinds, and, in the case of Wagner’s Die Walküre, twenty-two brass instruments. If you have ever been in the same room as a single trumpet, imagine competing with that and twenty-one of its friends. Opera singers, though, do not view it as a competition. Rather than trying to sing louder than a full orchestra, which would damage the voice, opera singers train to sing through it. In very simple acoustic terms, this is possible because the orchestra has an energy peak in its overtone series at around 500 Hz and the peak in a singer’s overtone series appears around 3000 Hz or at the singer’s formant. This phenomenon can be observed on spectrographs and is acquired through years of specialized training, in which singers learn (among other things) to drop the larynx, raise the soft-palate, relax the tongue, engage the core in new ways, and carefully manage the breath. Most people cannot consciously hear formants, but 500 Hz corresponds roughly to B4 and 3000 Hz, corresponds roughly to F#7. For reference middle C is C4 and a soprano’s high C is C6.
Energy distribution of an orchestra (black line) compared to that of an orchestra featuring a singing voice (dotted line). The figure comes from Sundberg (p. 123) [1].
The image below shows four Fs, in ascending fundamental frequency order, sung by the author, a soprano with 28 years of training, using “opera voice” - that is, standard, Western classical production. The fundamental frequencies, listed below each graph in text and Hz, are visible as the lowest squiggly line on each graph. In the first three, a cluster of energy around 3000 Hz can be seen clearly (circled in white).The fourth F, “The Queen of the Night” F, shows no singer’s formant. This phenomenon is in keeping with the findings of voice research, which predict that sopranos lose their formant at very high fundamental frequencies.
Formants, as described in this article, have the effect of increasing the amount of energy in a harmonic overtone or in a group of harmonic overtones. In the present case, they are due to a special resonance in the vocal tract that singers learn to create with their voice and which emphasizes certain overtones. One researcher who has extensively studied the singer's formant is Johan Sundberg, formerly of the Royal Institute of Technology in Stockholm.
To hear this in action, listen to the famous Ride of the Valkyries. In this video, the orchestra appears on stage with the singers, something that rarely happens in opera anymore, thanks to Wagner himself, who realized that placing the orchestra on a lower physical plane would give singers an extra acoustic edge. Placing the orchestra onstage removes this advantage, leaving the singer’s formant to do all the work. We begin at around 4 minutes, where the famous brass fanfare returns. At this point, the singers are in their middle ranges, where it can feel more difficult to project the voice. The orchestra is playing strongly, yet we hear the singers clearly, not more loudly than orchestra, but in partnership and audible throughout. In this second version, the score is visible, and we can observe exactly what the singers and orchestra are doing. Neither the singers nor the orchestra feel more prominent. Both can be heard distinctly. This happens, at least in part, because although it is usually abstracted from our conscious listening, the brain is able to use formant information to untangle the different sounds.
Ride of the Valkyries (Wagner, Die Walküre, Act 3), Version 1:
Hong Kong Philharmonic Orchestra
Conductor: Jaap van Zweden
Singers: Sarah Castle (Waltraute), Karen Foster (Gerhilde), Katherine Broderick (Helmwige), Anna Burford (Schwertleite), Elaine McKrill (Ortlinde), Aurhelia Varak (Siegrune), Okka von der Damerau (Grimgerde), Laura Nykänen (Rossweise)
Ride of the Valkyries (Wagner, Die Walküre, Act 3) Version 2:
Vienna Philharmonic Orchestra
Conductor: Georg Solti
Singers: Helga Dernesch (Ortlinde), Brigitte Fassbaender (Waltraute), Helen Watts (Schwertleite), Berit Lindholm (Helmwige), Vera Little (Siegrune) Christa Ludwig (Fricka), Marilyn Tyler (Grimgerde) Vera Schlosser (Gerhilde), Claudia Hellmann (Rossweisse)
REFERENCES
[1] Sundberg, J. (1987). The Science of the Singing Voice. Northern Illinois University Press.
[2] Sundberg, J. (1995). The singer’s formant revisited. Dept. for Speech, Music and Hearing. Quarterly Progress and Status Report, 36(2,3), 83-96.
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