The analysis of bird song is greatly assisted by being able to visualize the sounds. Most often this is achieved through a frequency spectrum analysis by plotting frequency (usually measured in kilohertz (kHz) against time, seconds (s), or milliseconds (ms)) to produce a "sonogram". The sonogram has become the standard way to illustrate a song and has enabled researchers to dissect the elements of individual songs in much greater details than otherwise possible. Thus the song of an individual can be analysed as its song repertoire develops over a season(s) and comparisons of song types produced by different individuals of a species can be compared.
Seeing sound: What is a spectrogram? Guidelines on how to read a spectrogram.
Click on the images below to view the sonograms.