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man_o_brass t1_j1egnvb wrote

Absolutely, although in practice, the frequency of the sounds would need to be fairly close to the limit of human hearing so that you wouldn't need to be going very fast. At very high speeds required for very high doppler shifts, wind noise would likely drown out what you were trying to hear.

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kilotesla t1_j1j4nf8 wrote

Adding to this, human hearing doesn't abruptly stop at a specific frequency, but becomes less and less sensitive as you go further to the extremes.

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Implausibilibuddy t1_j1fohz0 wrote

Not only can the doppler effect do this with sound, it works with light too. Red shift causes visible light waves to "stretch", lowering their frequency toward the red end of the spectrum. Due to the expansion of the universe the farthest and oldest light waves have undergone red shift so much that they're way past infrared into microwave territory. That's what cosmic background radiation is.

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[deleted] t1_j1g9kv7 wrote

[removed]

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droefkalkoen t1_j1hw2x3 wrote

To add to this: this is why the James Webb-telescope is such a great tool. It can 'see' much longer wavelengths and therefore can see more distant stuff.

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Doctor t1_j1eqoqv wrote

If the speaker is traveling away from you at the speed of sound, the frequency will be halved, that is, it will go down by one octave. So only the lowest bass will go out of hearing range. Also, it will be overwhelmed by the jet engine noise and will quickly fade into the distance.

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CrudelyAnimated t1_j1ff2te wrote

This is not a trick question, but it's a tricky situation. Sounds moving away from you become lower in volume by the inverse square law. So there's a perhaps rhetorical question whether you'd still be able to detect something moving that fast by the time it Doppler-shifted beyond processing. It absolutely works with light. Distant and fast-receding galaxies red-shift out of visible "colors" into infrared. You would need a very loud sound source, moving away very fast, with a starting frequency in the low end of your hearing range in the first place. There are people who can't intake below 30 or 40Hz, which is a whole octave above the typical healthy 20Hz lower limit. So results would vary across the population.

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