shriek vs titter

shriek

verb
  • To utter sharply and shrilly; to utter in or with a shriek or shrieks. 

  • To utter a loud, sharp, shrill sound or cry, as do some birds and beasts; to scream, as in a sudden fright, in horror or anguish. 

noun
  • An exclamation mark. 

  • A sharp, shrill outcry or scream; a shrill wild cry such as is caused by sudden or extreme terror, pain, or the like. 

titter

verb
  • To laugh or giggle in a somewhat subdued or restrained way, as from nervousness or poorly-suppressed amusement. 

noun
  • A nervous or somewhat repressed giggle. 

  • A woman's breast. 

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