concert vs unison

concert

noun
  • Agreement in a design or plan; union formed by mutual communication of opinions and views; accordance in a scheme; harmony; simultaneous action. 

  • A musical entertainment in which several voices or instruments take part. 

  • Musical accordance or harmony; concord. 

verb
  • To act in harmony or conjunction; to form combined plans. 

  • To plan; to devise; to arrange. 

  • To plan together; to settle or adjust by conference, agreement, or consultation. 

unison

noun
  • The state of being in harmony or agreement; harmonious agreement or togetherness, synchronisation. 

  • A sound or note having the same pitch as another, especially when used as the base note for an interval; a unison string. 

  • Identical pitch between two notes or sounds; the simultaneous playing of notes of identical pitch (or separated by one or more octaves). 

  • Two or more voices speaking the same words together. 

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