warble
US /ˈwɔːr.bəl/
UK /ˈwɔːr.bəl/

1.
gorjear, trinar
to sing in a soft, low voice, especially with a trilling or quavering sound
:
•
The bird began to warble a sweet melody.
O pássaro começou a gorjear uma doce melodia.
•
She would often warble old folk songs.
Ela frequentemente cantava canções folclóricas antigas.