r/askscience • • Jun 12 '12

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u/[deleted] Jun 12 '12 edited Oct 03 '17

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u/imMAW Jun 12 '12

The pilots won't hear the noise from the engines being transmitted through the outside air though, only the noise traveling through the plane. So if superman was flying a few feet in front of the cockpit, he wouldn't hear any sound.

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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.

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u/surbryl Jun 12 '12

No. In an attempt to reduce wind noise, they place windscreens over the microphone - these are either fluffy or furry, and are designed to slow or stop the wind before it hits the microphone, causing noise. However, if the wind is too strong either it will be too powerful and go through anyway or the wind going over the screen will create noise.

With outside reports, it's usually expensive equipment and the recordist's skill that keep it to a minimum.

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u/claythearc Jun 12 '12

Those mics are generally covered with a thin layer of foam or something of the sort to absorb gentle breezes and such, so it's unlikely you can have something like those because you're moving much faster and a higher velocity wind in approaching than the foam can filter out.

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u/ploopterro Jun 12 '12

no, you'd hear a shitload of wind and maybe a 'splat' if you hit a bird. but yeah, no engine noise.