STEM与日常科技·英语30篇（6）

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降噪耳机如何不堵耳朵也能制造静音

Active noise-canceling headphones use tiny microphones to pick up ambient sound waves before they reach your eardrums.
A digital signal processor then generates an ‘anti-noise’ wave with equal amplitude but opposite phase.
When the original and anti-noise waves meet, they cancel each other out through destructive interference.
This works best for steady, low-frequency sounds like airplane engines or air-conditioning hums.
Higher-pitched noises—such as voices or clattering dishes—require hybrid systems combining active and passive damping.
Battery life depends on continuous processing, so modern chips use ultra-low-power AI to predict and adapt to sound patterns.
Some models even adjust cancellation strength based on whether you’re walking, running, or sitting still.
Transparency mode reverses the process, letting outside sound in clearly—useful for street crossings or conversations.
Earcup design and seal quality still matter: poor fit leaks noise and weakens cancellation effectiveness.
Ultimately, physics, microelectronics, and ergonomic design all converge inside a pair of lightweight headphones.