patter
noun /ˈpætə(r)/
  /ˈpætər/
Idioms - [singular] the sound that is made by something repeatedly hitting a surface quickly and lightly
- the patter of rain on the roof
 - the patter of feet/footsteps
 - I could hear the pitter-patter of feet in the corridor.
 
 - [uncountable, singular] fast continuous talk by somebody who is trying to sell you something or entertain you
- sales patter
 
 
Word Originnoun sense 1 early 17th cent.: frequentative of pat (verb). noun sense 2 late Middle English (as a verb in the sense ‘recite (a prayer, charm, etc.) rapidly’): from paternoster, the Lord's Prayer, especially in Latin. The current sense dates from the mid 18th cent.
Idioms 
the patter of tiny feet 
- (informal or humorous) a way of referring to children when somebody wants, or is going to have, a baby
- We can't wait to hear the patter of tiny feet.