Final answer:
The third feature of the voice in a pop ballad is dynamic control, which allows the singer to expressively modulate volume and intensity, enhancing the emotional storytelling.
Step-by-step explanation:
The third feature of the voice in a pop ballad, following vibrato and melisma, would typically be dynamic control. Dynamic control refers to the singer's ability to modulate the volume and intensity of their singing expressively, which plays a critical role in conveying the emotional content of the song. In a ballad, where the focus is often on heartfelt storytelling, dynamic control allows the vocalist to emphasize certain words or phrases, drawing the listener into the narrative and evoking a stronger emotional response. For example, in a ballad like Adele's 'Someone Like You,' she starts the song softly and gradually increases the volume and intensity as the song progresses, creating a dynamic and emotional performance.