You may recognize the song being played as All Star, by Smash Mouth
and, if you do, something amazing is about to happen
Even though only piano notes are being played,
if you know the song, you'll start to hear the lead singer's voice
and the words being sung.
I swear, what you're hearing is 100% digital piano
simply matched to the frequency of the original song
and not mixed with real vocals.
and yet, you can hear the words.
This speaking piano shows a similar fenomenum.
It's hard to make out what it's saying, but
as soon as words are on screen, you begin to hear it talking.
Hearing is all about perception,
after a soundwave hits your ear, it's transformed into signals for your brain.
But your brain gets so many external signals that it can't process it all at once
and so it uses context to craft what you're hearing.
You hear the lyrics because the brain uses information it already has
to understand the world around you.
Which is why if you've never heard the song, it will sound like nonsense.
But, even without words, we sometimes hear things that aren't there.
Take this jumping transmission tower, for example.
Around 20% of people will actually hear a thud each time it lands
in a fenomenun known as visually evoked auditory response
Do you hear it?
It's a type of synesthesia
which is when the senses like hearing and sight get crossed in the brain.
Expectation is also playing a role here
A 2006 study scanned the brains of participants
who were told they'd eventually hear a sound
as they were listening to the silence and expecting to hear something,
the auditory cortex was activated in the same way
as when you were actually listening to sound.
So, do you hear it now?
Our brains are pretty good at filling in the gaps,
like in this audioclip.
But, now, listen to it with the cough removed.
There's literally a full syllable missing
but, with the cough, people tend to hear the entire word.
This illusion is known as "temporal induction".
Your brain fills in information to make sense of the world.
Now, listen to this rhythm.
Sounds like it's getting faster, doesn't it?
The thing is, it will seemingly get faster forever if I let it continue to play.
This is known as the "risset rhythm"
in which a beat starts relatively slow and starts to speed up
but, as it gets faster, beat 2 starts at exactly half the speed
and they increase in speed together.
Eventually, the faster one fades out as the slower one fades in,
and the loop continues.
But, your brain can't pick up the suddlety
and, as a result, it sounds like it's speeding up forever.
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