echo vs wah-wah

echo

noun
  • A reflected sound that is heard again by its initial observer. 

  • An individual discussion forum using the echomail system. 

  • An utterance repeating what has just been said. 

  • The displaying on the command line of the command that has just been executed. 

  • A signal, played in the same manner as a trump signal, made by a player who holds four or more trumps (or, as played by some, exactly three trumps) and whose partner has led trumps or signalled for trumps. 

  • An antisemitic punctuation symbol or marking, ((( ))), placed around a name or phrase to indicate the person is Jewish or the entity is controlled by Jewish people. 

  • A device in verse in which a line ends with a word which recalls the sound of the last word of the preceding line. 

  • A signal showing the number held of a plain suit when a high card in that suit is led by one's partner. 

  • Sympathetic recognition; response; answer. 

verb
  • To reflect off a surface and return. 

  • To repeat (another's speech, opinion, etc.). 

  • To reflect back (a sound). 

  • To repeat its input as input to some other device or system. 

  • To give the echo signal, informing one's partner about cards one holds. 

wah-wah

noun
  • A wavering sound produced by means of a movable mute or by electronic means 

verb
  • to make a wah-wah sound 

intj
  • The sad trombone sound, used to indicate failure or disappointment. May be used mockingly; also written wah wah and womp womp. 

adj
  • Modifying the resonance of musical notes to produce the effect of a human voice. 

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