DIY Friday: Noise-cancelling Headphones
Noise Cancelling Headphones – they appear to be the newest trendy gadget, popping up everywhere in electronic stores and inflight catologs. But, damn, they can be expensive. Before we can get to the do-it-yourself option, let’s take a look at how they work:
Noise-cancelling headphones reduce unwanted ambient sounds (i.e., acoustic noise) by means of active noise control (ANC). Essentially, this involves using a microphone, placed near the ear, and electronic circuitry which generates an “antinoise” sound wave with the opposite polarity of the sound wave arriving at the microphone. This results in destructive interference, which cancels out the noise within the enclosed volume of the headphone.
Howstuffworks has a more detailed explanation, complete with graphics reminiscent of a high school physics course.
Now, if you not only aced that high school physics course, but also kept it going in college, you might be able to build a pair of headphones by following these complicated directions.
For the more modest, you could skip the physics and just hack together a pair using some industrial earmuffs for just $20 dollars:
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