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Gripped with vengeful passion,

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The Queen of the Night tears 
across the stage.

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She begins to sing her titular aria,

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one of the most famous sections from
Mozart’s beloved opera, The Magic Flute.

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The orchestra fills the hall with music,

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but the queen’s voice soars above 
the instruments.

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Its melody rings out across thousands 
of patrons,

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reaching seats 40 meters away— all 
without any assistance from a microphone.

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How is it possible that this single voice
can be heard so clearly,

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above the strains of dozens 
of instruments?

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The answer lies in the physics of the 
human voice,

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and the carefully honed technique 
of an expert opera singer.

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All the music in this opera house 
originates from the vibrations

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created by instruments—

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whether it’s the strings of a violin 
or the vocal folds of a performer.

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These vibrations send waves into the air, 
which our brains interpret as sound.

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The frequency of these vibrations––

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specifically, the number of 
waves per second––

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is how our brains determine the 
pitch of a single note.

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But in fact, every note we hear

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is actually a combination 
of multiple vibrations.

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Imagine a guitar string vibrating at its
lowest frequency.

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This is called the fundamental,

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and this low pitch is what our ears 
mostly use to identify a note.

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But this lowest vibration triggers 
additional frequencies called overtones,

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which layer on top of the fundamental.

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These overtones break down into specific 
frequencies called harmonics, or partials–

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and manipulating them is how 
opera singers work their magic.

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Every note has a set of frequencies that
comprise its harmonic series.

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The first partial vibrates at twice the 
frequency of the fundamental.

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The next partial is three times the 
fundamental’s frequency, and so on.

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Virtually all acoustic instruments 
produce harmonic series,

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but each instrument’s shape and material
changes the balance of its harmonics.

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For example, a flute emphasizes the 
first few partials,

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but in a clarinet’s lowest register,

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the odd-numbered partials 
resonate most strongly.

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The strength of various partials

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is part of what gives each instrument
its unique sonic signature.

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It also affects an instrument’s ability 
to stand out in a crowd,

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because our ears are more strongly 
attuned to some frequencies than others.

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This is the key to an opera singer’s power
of projection.

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An operatic soprano— the highest 
of the four standard voice parts—

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can produce notes with fundamental
frequencies

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ranging from 250 to 1,500 vibrations 
per second.

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Human ears are most sensitive to 
frequencies

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between 2,000 and 5,000 
vibrations per second.

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So if the singer can bring out the partials 
in this range,

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she can target a sensory sweet spot 
where she’s most likely to be heard.

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Higher partials are also advantageous

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because there’s less competition 
from the orchestra,

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whose overtones are weaker at 
those frequencies.

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The result of emphasizing these 
partials

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is a distinctive ringing timbre 
called a singer’s squillo.

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Opera singers work for decades to 
create their squillo.

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They can produce higher frequencies

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by modifying the shape and tension 
in their vocal folds and vocal tract.

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And by shifting the position of their 
tongues and lips,

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they accentuate some overtones 
while dampening others.

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Singers also increase their range of 
partials with vibrato––

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a musical effect in which a note slightly 
oscillates in pitch.

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This creates a fuller sound that rings 
out

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over the instruments’ comparatively
narrow vibratos.

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Once they have the right partials,

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they employ other techniques to 
boost their volume.

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Singers expand their lung capacity and
perfect their posture

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for consistent, controlled airflow.

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The concert hall helps as well,

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with rigid surfaces that reflect sound 
waves towards the audience.

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All singers take advantage of these 
techniques,

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but different vocal signatures demand 
different physical preparation.

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A Wagnerian singer needs to build up 
stamina

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to power through the composer’s 
four-hour epics.

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While bel canto singers require versatile 
vocal folds

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to vault through acrobatic arias.

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Biology also sets some limits—

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not every technique is feasible for every
set of muscles,

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and voices change as singers age.

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But whether in an opera hall or a 
shower stall,

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these techniques can turn unamplified 
voices

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into thundering musical masterpieces.