Song sparrows adjust their songs to fit in with urban noise

While at Reed College in Oregon, Yezerinac and student William E. Wood examined the effects of urban noise on the song sparrow songs of Portland. They recorded 28 birds in areas with various levels of background noise, carefully measuring frequency (pitch) and amplitude (volume; the amount of energy invested in making a sound).

Birds in the noisiest spots were more likely to cede some of their lower frequencies to background noise, while their songs' higher-frequency notes remained constant.