Why do earplugs amplify internal noises?
The bigger a drum’s body, the deeper is its sound – it’s all about the sound box.
Asked by: David Mellish, King’s Lynn
This is called the occlusion effect. Normally, the sounds of your own breathing, chewing and swallowing are mostly transmitted through the bones of your jaw and skull. These vibrations, especially the lower frequency ones, are dissipated outwards by the shape of your ear. But if you block your ears with your fingers or earplugs, you create a resonating chamber between your eardrum and the blockage. It’s not just that inside noises sound louder by comparison with the muffled sounds from outside, there is a real, measurable amplification of up to 20 decibels.
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Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.
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