Final answer:
Ariel's invisibility and music create dramatic tension and conflict in the plot, demonstrate his magical powers, and embody a metaphor for freedom.
Step-by-step explanation:
The relationship between Ariel's invisibility and his music serves to advance the plot by creating dramatic tension and conflict. When Ariel is invisible, this element of the supernatural becomes a driving force behind the actions and reactions of the other characters. The music associated with Ariel often sets the mood or supports the themes of the scenes, such as freedom, or deception. In theatrical productions, the use of lighting and revealing of theatrical instruments can enhance the illusion or highlight the artifice of the performance, much like Ariel's magic does in the story.
Furthermore, this invisible music also aids in demonstrating Ariel's magical abilities. It is a direct example of how Ariel's supernatural powers can affect the physical world and the characters within it. Lastly, Ariel's control over his visibility and his enchanting music can be seen as a metaphor for freedom—the freedom from physical constraints and the freedom to influence others without being seen.