How Do Noise-Canceling Headphones Work? (film, 3 minutes)
In the latest video released by BBC, an intriguing topic of active noise cancelling is presented. The author begins by demonstrating how this technology works by using two speakers. He starts by playing a tone through one speaker and then adds another one while reversing the wires. Logically, one might assume that adding a speaker would make the sound louder. To the viewers' surprise, when the second speaker is connected, the sound actually becomes quieter. This surprising change happens due to the inversion of the sound wave. Both speakers are playing the same sound, but since one is connected in the opposite way, it creates a wave that is the exact opposite of the first. As a result, the sound cancels itself out, leading to an ideal silence.
The author explains next that this process is a key mechanism in active noise cancelling headphones. The microphones in the headphones pick up unwanted sounds, which are then inverted and played back, effectively eliminating the original noise. This allows users to focus only on the sounds they wish to hear. This mechanism works similarly regardless of the conditions, providing an effective solution to enjoying audio in noisy environments.
Active noise cancelling has applications across various fields, not just in headphones. It can be utilized in airplane engines, car audio systems, and other audio devices where silence is desirable. This makes the technology highly sought after in everyday use since it allows for enjoying music, podcasts, or phone conversations without disturbances from the environment.
In summary, active noise cancelling technology not only enhances sound quality but also transforms the way we perceive the world of sounds around us. The more skills developed within this technology, the better control we have over what we hear. As of the time writing this article, the video on BBC's channel has reached 250468 views and 6619 likes, indicating a significant interest in this topic among viewers.
Active noise cancelling is undoubtedly one of the most exciting technological advancements that not only improve our quality of life but also become incredibly popular in the audio industry. The author encourages viewers to watch the video and learn more about this fascinating technology.
Toggle timeline summary
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Introduction to active noise cancelling technology.
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Demonstration of sound through one speaker.
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Plugging in a second speaker to observe sound changes.
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Initial expectation of sound increase with additional speaker.
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Surprise moment: sound becomes quieter instead of louder.
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Explanation of wiring the second speaker oppositely.
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Sound wave's visual representation.
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Adding a third speaker expected to increase sound.
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The resulting sound wave from the flipped second speaker.
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Overall effect: cancellation of noise leading to silence.
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Explanation of how active noise-cancelling headphones function.
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Overview of microphone function in cancelling noise.
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Conclusion on what is played through the earbuds.
Transcription
There is something that is called active noise cancelling, and it's a very, very clever thing. So, OK, I'm going to play a tone through one of these speakers. I mean, not particularly pleasant to the ear. And now what I'm going to do is I'm going to plug in the second speaker and see if you can notice what happens to the sound as I do. Logic might make you think that adding a speaker will make it louder. OK, it's going in now. Did you hear that? Let me just unplug it and plug it in again. Can you hear that? You've got double the number of speakers playing exactly the same sound, and yet... ..instead of it getting louder... ..it actually gets quieter. So, what is going on? Well, when I hooked up that second speaker, I switched around its wires at the back, meaning it's wired up in the opposite way to speaker one. So, I'm essentially putting in... ..the inverse, the exact opposite of what's coming out here. Do you see that? The tone sounds the same, and it's the same volume, but the sound wave has been flipped upside down. This is the shape that the wave is making. That's like the sound wave wobbling in the air. Now, OK, if I put in another speaker, of course this wave's going to get bigger, right? It's just going to get louder. But because I've wired in speaker the wrong way around, the second speaker ends up making that same wave, but flipped upside down. So, this one up here ends up being cancelled out by this one down here, and so what you end up with, in ideal circumstances, is a complete flat line through the middle. No noise at all. The noise is cancelled by playing the same sound, just flipped. This is how all active noise-cancelling headphones work. Microphones pick up unwanted sounds, which get flipped and played back to cancel out the original noise. All that's coming through your earbuds is what you are choosing to listen to.