Step-by-step explanation:
The section of an opera, oratorio, or cantata that is known for quick sections of text with speech-like repeated notes sung over sustained chords is called the "Recitative."
Recitative is a style of vocal music that falls between a spoken dialogue and a fully sung aria. It is often used to advance the plot, convey dialogue or narrative information, and provide a transition between different musical sections. In recitative, the singer follows the natural rhythms and inflections of speech, accompanied by simple harmonic accompaniment or sustained chords from the orchestra or continuo.
The repeated notes in the vocal line of the recitative create a speech-like, conversational effect, allowing the singer to convey the text in a more spoken manner while still remaining musically expressive. This style of singing is particularly prominent in storytelling or dialogues within operas, oratorios, and cantatas.