Males sing a sweet series of 6–10 whistled notes that accelerate over the course of the roughly 1-second song and often end on a rising note. The tone is so sweet that people often remember it with the mnemonic sweet sweet sweet I’m so sweet. The songs are a common sound of spring and early summer mornings and may be repeated as often as 10 times per minute.
Yellow Warblers use a variety of short chip notes, some with a metallic sound and some with a lisping or buzzing quality. Males sometimes alternate chip notes with their songs, and females may answer a song with a high-pitched chip. Both sexes use a high, hissing note in territorial defense, and may confront cowbirds with a seet call.