The top 25 most common West Coast US birds, ranked by how pure their song or call sounds — how close it is to a clean whistled tone versus a harsh, noisy, broadband screech. Flute-throated thrushes at the top. Crows and jays, who scream in static, at the bottom.
What "pure" means here: a whistled note is (acoustically) close to a single sine tone — a clean fundamental frequency with few overtones. A caw or screech is broadband noise — energy smeared across many frequencies at once, the same reason a cymbal crash and a flute look completely different on a spectrogram. Real acoustics; extremely biased vibes-based tiering on top of it.