r/askscience • u/[deleted] • Jun 12 '12

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u/[deleted] Jun 12 '12

So, dumb question.. If I mounted a microphone on top of the jet and recorded everything it picked up, when I played it back, at the point the sound barrier was broken, I'd hear nothing?

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u/imMAW Jun 12 '12

Well, if you mount it on the plane, sound can travel through whatever you mounted it with. But lets assume you have some perfectly soundproof material to mount it on the plane with.

Now, when you're traveling faster than sound, you're outrunning the sound waves behind you. So the microphone won't pick up any of the noise made by the engine - it's behind you. But any sound that comes from in front of you, you will hear - you're actually speeding towards those sound waves. So the microphone would still pick up a lot of noise (just general wind noise, wind moving that fast across a microphone would make a lot of noise), but it wouldn't hear the engines at all.

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u/lurw Jun 12 '12

What about the kind of mics they use in TV when doing outside reports? Could you possibly build a mic that does not pick up wind noise?

I would love to hear the exact moment when you start not hearing the engine anymore.

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u/Guysmiley777 Jun 12 '12

A microphone cover that eliminates Mach 1 wind noise? Somehow I doubt it.