transcript: Many of us have become quick to catch illusions
that trick our eyes - but how often do you consider illusions of the ear? Are you really
able to trust your ears and the things they hear? For example, listen to Greg speaking... What do you hear? If you heard 'bar, bar,
bar' you'd be right. But, how about now? Chances are you heard 'far, far, far' this time, with an 'F'. Except, you didn't - in fact, the audio didn't even change between the two videos. Strange as
it seems, what you hear depends on which video you are looking at. Go ahead - take turns
watching each video and see how the sound morphs. This is a perfect example of something
called the McGurk effect, which shows how our visuals can alter what we believe we're
hearing. Now I want you to count how many times you
see a circle flash on screen. Lets do that once more time. Did you see it flash twice?
Many people do. Yet, without the sound, it becomes clear that the circle is only flashing
once. In this case, the sound has altered your perceived vision. This next one works best with other people
around. I'll play two tones, and you tell me if they are ascending or descending. In
other words, are the notes played from low to high, or high to low? Listen to this. Which was it? How about this one? Write down what you heard for each number, and let
us know in the comments. Chances are, if you compare with enough people, you'll all have
different answers. Surprising? Try some more. And this one. How is it possible that you're hearing something different from others? It's an auditory illusion called the
Tritone Paradox. It's created in such a way that the tones contains both a higher and
lower frequency in them, but our brains have a preference of which to listen to. Diana
Deutsch, the creator of this illusion, found that your geography and language from infancy
all play a role in deciding this preference. Finally, listen to this audio clip of a gradually climbing tune. And yet, if I play the exact same clip back to you, it will sound like
it's only continuing to climb higher and higher. I swear this is the exact same clip I just
played - you can rewind that section of this video over and over and check yourself. Try
it! Each time you start it over, the tune is seemingly climbing even higher. It's called
the Shepard Tone Illusion, of which there are many variations. In it, multiple sine
waves are played on top of one another raising in pitch, while one quickly drops down an
octave as the others continue rising. But our brain doesn't notice this drop, and so
the clips sound like they are rising...forever! These illusions may help to explain how something
like music can have such a profound yet varying effect on our minds, which we discuss in our
new AsapTHOUGHT episode here, along with the question of whether or not Music Can Save Your Life.
There's a link in the description to watch it! So...do you still trust your ears? Got a burning question you want answered? Ask it in the comments or on Facebook or Twitter. And if you want the inside scoop on upcoming episode ideas and behind the scenes, check out our personal Instagram and Twitter handles. And subscribe for more weekly science videos!
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