For long range communication an elephant uses a low frequency rumble that is undetectable to human ears. One elephant can pick up another elephant's call from a distance of 10 km. The frequency of this rumble is about 13 Hz. How fast does the rumble travel?
Physics - Elena, Tuesday, May 22, 2012 at 4:50am
The speed of sound doesn't depend on the distance of propagation. It depends on the properties of the medium, particulary, on the temperature. So, it is ~ 343 m/s.