plip vs whirr

plip

noun
  • A light sound or action like liquid hitting a surface. 

verb
  • To make the sound of liquid hitting a hard surface. 

  • To lock or unlock using a remote control locking device. 

whirr

noun
  • A sibilant buzz or vibration; the sound of something in rapid motion. 

  • A bustle of noise and excitement. 

verb
  • To make a sibilant buzzing or droning sound. 

  • To cause (something) to make such a sound. 

  • To move or vibrate (something) with a buzzing sound. 

How often have the words plip and whirr occurred in a corpus of books? (source: Google Ngram Viewer )