The loudness depends on the amplitude of the vibration. It will be louder when the amplitude is high. Suppose when we pluck a string of the sitar it starts vibrating with low amplitude and if we apply more energy by plucking more strongly, the string will vibrate with the greater amplitude and produce a loud sound.
-- The loudness of the vibration is determined by its <em>amplitude</em>.
-- The pitch of the vibration is determined by its <em>frequency</em>.
-- The amplitude and frequency of the vibration are determined by the material characteristics of the body that's vibrating, and by how much energy is used to start the vibrations.
If you could please give me a already given speed I could estimate it. since there is no speed shown you wouldn't be able to estimate the speed of the moving train.