Is 391 meters per hour as fast as The Speed of Sound?
It's about one-three-thousandth as fast as The Speed of Sound
The speed of The Speed of Sound is about 1,230,000 meters per hour.
(in dry air at 20°C)
The speed of sound in dry air at 20°C (68°F) is 1,230,000 meters per hour. Air is a relatively poor acoustic conductor, however, as sound will travel at speeds of between 5,390,000 meters per hour to 5,620,000 meters per hour in water, depending on its salinity.
There's more! See other comparisons to 391 meters per hour...