noun / verb
warble
WOR-bul/ˈwɔːrbl/
A song or sound with rapidly varying notes, or to produce it.
The man warbles into the microphone as his voice rises and falls repeatedly.

Etymology
Werbler described singing with trills and quavers. English’s earliest recorded use referred to a trumpet, showing that the central idea was wavering musical sound, not exclusively vocal song.
In context
gay- plumaged birds of all sorts began to warble in the trees
More examples
- She warbles a cheerful tune as she washes the dishes.
- The bird's warble rises above the noise of traffic.
- The radio gives a brief warble before the signal fades.
Forms
warble · warbles · warbled · warbling
warbler noun — A small songbird known for its singing.
Similar words
- trill
- Emphasizes rapid alternation between two notes rather than broader variations.
- quaver
- Emphasizes a trembling sound rather than a melodious series.