What’s a squillo, and why do opera singers need it? - Ming Luke
Gripped with vengeful passion,
The Queen of the Night
tears across the stage.
She begins to sing her titular aria,
one of the most famous sections
from Mozart’s beloved opera,
"The Magic Flute."
The orchestra fills the hall with music,
but the queen’s voice soars above
the instruments.
Its melody rings out
across thousands of patrons,
reaching seats 40 meters away—
all without any assistance
from a microphone.
How is it possible that this single voice
can be heard so clearly,
above the strains
of dozens of instruments?
The answer lies in the physics
of the human voice,
and the carefully honed technique
of an expert opera singer.
All the music in this opera house
originates from the vibrations
created by instruments—
whether it’s the strings of a violin
or the vocal folds of a performer.
These vibrations send waves into the air,
which our brains interpret as sound.
The frequency of these vibrations––
specifically, the number
of waves per second––
is how our brains determine
the pitch of a single note.
But in fact, every note we hear
is actually a combination
of multiple vibrations.
Imagine a guitar string vibrating
at its lowest frequency.
This is called the fundamental,
and this low pitch is what our ears
mostly use to identify a note.
But this lowest vibration triggers
additional frequencies called overtones,
which layer on top of the fundamental.
These overtones break down
into specific frequencies
called harmonics, or partials—
and manipulating them
is how opera singers work their magic.
Every note has a set of frequencies
that comprise its harmonic series.
The first partial vibrates
at twice the frequency of the fundamental.
The next partial is three times
the fundamental’s frequency, and so on.
Virtually all acoustic instruments
produce harmonic series,
but each instrument’s shape and material
changes the balance of its harmonics.
For example, a flute emphasizes
the first few partials,
but in a clarinet’s lowest register,
the odd-numbered partials
resonate most strongly.
The strength of various partials
is part of what gives each instrument
its unique sonic signature.
It also affects an instrument’s ability
to stand out in a crowd,
because our ears are more strongly
attuned to some frequencies than others.
This is the key to an opera singer’s
power of projection.
An operatic soprano—
the highest of the four standard
voice parts—
can produce notes
with fundamental frequencies
ranging from 250 to 1,500 vibrations
per second.
Human ears are most sensitive
to frequencies
between 2,000 and 5,000
vibrations per second.
So if the singer can bring out
the partials in this range,
she can target a sensory sweet spot
where she’s most likely to be heard.
Higher partials are also advantageous
because there’s less competition
from the orchestra,
whose overtones are weaker
at those frequencies.
The result of emphasizing
these partials
is a distinctive ringing timbre
called a singer’s squillo.
Opera singers work for decades
to create their squillo.
They can produce higher frequencies
by modifying the shape and tension
in their vocal folds and vocal tract.
And by shifting the position
of their tongues and lips,
they accentuate some overtones
while dampening others.
Singers also increase their range
of partials with vibrato—
a musical effect in which a note
slightly oscillates in pitch.
This creates a fuller sound
that rings out
over the instruments’
comparatively narrow vibratos.
Once they have the right partials,
they employ other techniques
to boost their volume.
Singers expand their lung capacity
and perfect their posture
for consistent, controlled airflow.
The concert hall helps as well,
with rigid surfaces that reflect
sound waves towards the audience.
All singers take advantage
of these techniques,
but different vocal signatures
demand different physical preparation.
A Wagnerian singer needs
to build up stamina
to power through the composer’s
four-hour epics.
While bel canto singers require
versatile vocal folds
to vault through acrobatic arias.
Biology also sets some limits—
not every technique is feasible
for every set of muscles,
and voices change as singers age.
But whether in an opera hall
or a shower stall,
these techniques can turn
un-amplified voices
into thundering musical masterpieces.
