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We put the spotlight on high-frequency soundwaves
to a single pair of unsuspecting ears.
Dr. Joe Pompeis is an unassuming MIT grad,
who has the powers of a superhero.
He can whisper directly in the ears of
patrons at the local library.
From way up on the balcony.
Ok, let's try the guy with the green jacket.
Hey. Hey you. Just be aware that we're keeping an eye on you.
So you better cut it out.
Pompeis achieves this seemingly superhuman feat,
with a gizmo he invented called the Audio Spotlight.
It's a speaker that focuses sound at a specific target.
Pompeis was your average teenager,
always tweaking his stereo equipment,
but with a twist:
he had a gift for engineering and design.
He made an incredible scientific breakthrough
that began when he was working a summer job at an audio company.
I started becoming interested in really what shortcomings
with traditional loudspeakers were.
He realized that regular loudspeakers
can create directional sound.
A loudspeaker is like the lightbulb.
The sound that's created really goes everywhere.
The young engineer wanted to direct sound,
just like a laserpointer that you confuse cats with.
He figured out that mathematically there are
only two options to make speakers
act like lasers.
Use gigantic speakers,
or only broadcast high-frequency audiowaves.
The same frequencies that Howard Stapleton used
to deter teens in Connection 2.
The reason lies in the way audiowaves travel through the air.
Low-frequency audiowaves, like bass sounds,
have more time to spread out over a larger area as they travel.
Short high-frequency waves reach their targets faster,
so to get a speaker to beam its sound across the room,
you can only use high-frequency sound.
But as we learn in our first connection,
high-frequency sounds frighten people away.
And that wasn't what Pompeis was trying to do.
So he needed another option.
In order to create a sound source that's directional,
either you have to limit it only to extremely high frequencies,
or you need to have a loudspeaker thats tens of meters across.
When you create a speaker that big,
certainly the beam is that big.
So it doesn't do very well when you want to target
one person, or one small area.
It seemed that Pompeis' project was doomed.
It's very rare in science to get to a stopping point
where you realize that
according to the math and according to all known theory,
something's just not possible.
Undaunted, Pompeis' persistence resonated
with the media lab of MIT.
They accepted him into their doctoral program
and directed him towards an exciting new possibility.
Using ultrasound waves to create his audio beam.
Ultrasound waves are even shorter than
Howard Stapleton's high-frequency audio in Connection 2.
They're so fast and small that no one,
not even a teenager, could hear them.
And their tiny quick nature also makes them highly directional.
If Pompeis could convert ultrasound into audible sound,
he'd be able to direct it like a laser beam.
Several sleepless nights later,
he finally made the math work.
Here's his theory:
Air is always moving, even in a still room.
These air current deflect soundwaves as they travel.
Mathematically there was a way to accurately predict
how these air currents would strike the ultrasound waves,
and convert them into frequencies that we can actually hear.
Since the ultrasound waves are highly directional,
the resulting aim of the audible sound was perfect.
The possibilities of this device were endless.