I have been experimenting with processing birdsong in the Audacity sound editor. This is a very powerful and free program which is great for recording and cleaning up audio and inspecting its frequency spectrum. I used the Audacity spectrogram to generate a 3D model that you can view in your browser.
Click on the image below to view the 3D spectrogram. Zoom in with your mouse wheel and click-drag to rotate the view. The robin sings once at 1x speed and then again at half speed so you can follow the detail.
BTW, this was recorded on my £15 Logitech C270 webcam feeding in to Audacity. I set Audacity up to record automatically at 4am and stop at 8am.