quaver vs tremolo

quaver

noun
  • A trembling of the voice, as in speaking or singing. 

  • A trembling shake. 

  • an eighth note, drawn as a crotchet (quarter note) with a tail. 

verb
  • To shake in a trembling manner. 

  • To use the voice in a trembling manner, as in speaking or singing. 

  • To utter quaveringly. 

tremolo

noun
  • A variation in the volume of a note or a chord, evoking a tremor or quiver. 

  • The device in an organ that produces a tremolo effect. 

  • A rapid repetition of the same note, or an alternation between two or more notes. It can also be intended to mean a rapid and repetitive variation in pitch for the duration of a note. It is notated by a strong diagonal bar across the note stem, or a detached bar for a set of notes (or stemless notes). 

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