Your ears are lying to you right now. In this episode of The Rest Is Science, Professor Hannah Fry and Michael Stevens (Vsauce) dive into the bizarre world of audio illusions where your brain hears so
Another really cool thing about rhythm sped up into a tone is that harmonious polyrhythms also happen to make harmonious note combinations when sped up. What sounds complimentary to us as a set of overlapping beats mirrors what essentially makes up chords in music.
You can see a visual analog of the brainstorm/green needle illusion if you stare at tv static and imagine a shape, that shape will emerge and bounce around in the static. It can literally be any shape you can concentrate on
5:18 Sound engineer here. I would also like to add that a single sound sample has multiple frequencies in it, so sound usually is not just one type of waveform, but infinite amount of sine waves combined (except for the sine wave itself which doesn't contain harmonics). The beating is caused by the sudden rise and fall in amplitude (which also occurs when someone edits the waveform or does granular synthesis in an unprofessional way). But if the amplitude difference is small, then you can't hear the beating. You can't hear the beating at 1 Hz for a sine wave or a triangle wave for example, because the change is so smooth. So, I think, waves are not just a bunch of beats by definition. There's more to that.
And you can also hear beating if you play two sine waves close to each other in frequency. For example 440 Hz and 441 Hz, you'll hear a 1 Hz beating. If you increase the frequency difference, then it becomes two different tones played alongside each other, and they become a chord.
Also, as far as I know, the haircells receive the sound, and they are physically moved by the air pressure differences that the sound makes. But it's a good question how exactly it's processed in the
I have never experienced a show like this. I'm completely blown away by how much every episode completely grips me. You guys are unlocking a new requirement in my life and I need to have more.
I think the initial discussion failed to take into account that our brain does not really receive audio signals from the ears in the *temporal space*, but instead in the *frequency space*.
What I mean is, our ears don't really detect "air displacement over time", instead they directly detect frequencies with resonating hairs. Any 400 Hz repetition patterns will resonate with the "400-Hz hairs" and send signals that represent 400 Hz directly to the brain. So, it feels kind of wrong characterising this as something that happens purely in the mind, when much is physically happening in the ear.
(Because of the number of straw men in the replies, let me be more clear: the part that I have the most problem with is when Michael said, at 4:43, that our brain gives up / fails and just "make it a pitch". That's just incorrect. To the brain, it IS already a pitch to begin with. Our brain makes no extra efforts in interpreting the audio signal as a pitch, not any more than, say, interpreting a pain signal from your finger as pain from your finger, or sweet signal from your tastebud as sweetness. This episode is about how we don't experience reality. But the pitch is the reality in this case.
Did anyone else still only hear laurel when the bottom tones were removed?
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And you can also hear beating if you play two sine waves close to each other in frequency. For example 440 Hz and 441 Hz, you'll hear a 1 Hz beating. If you increase the frequency difference, then it becomes two different tones played alongside each other, and they become a chord.
Also, as far as I know, the haircells receive the sound, and they are physically moved by the air pressure differences that the sound makes. But it's a good question how exactly it's processed in the
NOTHING:
* dead silence *
editors did him dirty 😭
What I mean is, our ears don't really detect "air displacement over time", instead they directly detect frequencies with resonating hairs. Any 400 Hz repetition patterns will resonate with the "400-Hz hairs" and send signals that represent 400 Hz directly to the brain. So, it feels kind of wrong characterising this as something that happens purely in the mind, when much is physically happening in the ear.
(Because of the number of straw men in the replies, let me be more clear: the part that I have the most problem with is when Michael said, at 4:43, that our brain gives up / fails and just "make it a pitch". That's just incorrect. To the brain, it IS already a pitch to begin with. Our brain makes no extra efforts in interpreting the audio signal as a pitch, not any more than, say, interpreting a pain signal from your finger as pain from your finger, or sweet signal from your tastebud as sweetness. This episode is about how we don't experience reality. But the pitch is the reality in this case.
I hear nothing but laurel all three times
... "Laurel.. Laurel"