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When an aircraft breaks the sound barrier, can the pilot hear anything (because I guess the sound would be travelling behind him, being left behind. Would it?)
Basically, sound is slower than light, yes? So when this aircraft goes faster than sound, the sound couldn't keep up with the aircraft. Does that mean the aircraft pilot can't hear anything, because obviously the sound would be behind him (i think?)???
asked in physics, sound, aircraft

athenabs13ohe answers:

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The opposite is true in a subsonic flow below the speed of sound. In this case, sound travels outward in all directions at the same rate. A good way to visualize this behavior is to recall the ripples created by dropping a rock into a pond. The ripples appear as circles formed evenly around the point were the rock impacts the surface of the water and spread outward in all directions at the same speed. When a person speaks, the sound waves behave in the same way. It is for this reason that we can hear a person talking whether he is in front of us or behind us.
Getting back to passengers aboard a plane, the sound waves they create as they speak behave no differently than if they were having a conversation while sitting at home around the dining room table. In both cases, the air around the people is at rest. Even though the air outside the plane may be moving by at incredible supersonic speeds, the air inside the cabin or cockpit is not moving with respect to the people inside. The internal air is therefore subsonic and sound waves travel in all directions like ripples on a pond rather than in only one direction like shock waves.
Now if the nose of the aircraft was to somehow vanish and the people inside were suddenly exposed to supersonic air, any sounds they made would travel like shock waves instead of ripples. In this case, a person sitting at the back of the plane would be able to hear sounds made by someone at the front, but that person at the front would not be able to hear anything said by those behind him. This example is rather hypothetical, however, since sudden exposure to a supersonic flow like that experienced outside an aircraft would produce intense and fatal forces on the human body. Being able to hear what your friend at the other end of the plane was saying would be the least of your concerns

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Messerwisser answers:

Have you noticed that speech and music sounds normal in a travelling car? Why not any Doppler effect? (Compare with the sound from the sirens of a passing police car.
Because the air in the car is moving with the car. The same goes for the air plane. Sounds in the cabin are normal, but the pilot can not hear the noise the air plane is making on the outside.

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blacksmith81 answers:

Aircraft breaking the Sound Barrier

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