chirl vs chirp

chirl

verb
  • To emit a low sound; to warble. 

noun
  • A kind of musical warble. 

chirp

verb
  • To speak in a high-pitched staccato. 

  • To make a short, sharp, cheerful note, as of small birds or crickets. 

  • To modify (a pulse of signal) so that it sweeps through a band of frequencies throughout its duration. 

  • To speak rapid insulting comical banter back and forth. 

noun
  • A pulse of signal whose frequency sweeps through a band of frequencies for the duration of the pulse. 

  • A short, sharp or high note or noise, as of a bird or insect. 

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