@TheBreadmonkey

For your ears to detect this effect—called the Doppler effect—the sound source has to be moving toward or away from you at a minimum speed of about 15 to 20 mph (24 to 32 kph). As the source moves faster, the effect becomes more pronounced.

https://www.exploratorium.edu/snacks/doppler-effect

The fastest human ever recorded is Usain Bolt, who reached a peak speed of 27.8 mph (44.7 km/h)

@spanghero @scribblanitea