I research birds, and I make art from spectrograms of bird song that I've recorded. A spectrogram is a way to visualize sound. It's like a waveform, except that instead of showing you volume over time, it's showing you frequency over time. When we speak, we make broad stacks of harmonics. Songbirds are able to tightly control their vocalizations, which is how you see such delicate and beautiful lines of sound.