In chapter one of The Great Gatsby, Nick describes his cousin Daisy's voice (12):
I looked back at my cousin who began to ask me questions in her low, thrilling voice. It was the kind of voice that the ear follows up and down as if each speech is an arrangement of notes that will never be played again. Her face was sad and lovely with bright things in it, bright eyes and a bright passionate mouth—but there was an excitement in her voice that men who had cared for her found difficult to forget: a singing compulsion, a whispered ‘Listen,’ a promise that she had done gay, exciting things just a while since and that there were gay, exciting things hovering in the next hour.
In essence, Nick is describing the musicality of Daisy's voice - men go crazy for her since it's so enticing. Her voice made promises of exciting things to come. The connotation of the words in this description is generally positive - "thrilling," "arrangement of notes," "bright," "excitement," "singing," etc. Considering Gatsby's history with Daisy, it only makes sense why he fell so hard for her.
Towards the end of the novel, however, Gatsby remarked that Daisy's voice was "full of money," which made a lot of sense to Nick (128):
That was it. I’d never understood before. It was full of money—that was the inexhaustible charm that rose and fell in it, the jingle of it, the cymbals’ song of it…. High in a white palace the king’s daughter, the golden girl….
Nick now has a different view of Daisy's voice. The source of her charm was money. While the first description had a more positive connotation, this description contains more negative connotations, specifically the word "inexhaustible." Nick compares Daisy to a king's daughter up high in a palace. This creates an image that Daisy is untouchable or unreachable even though she is able to charm people with her voice. Comparing her to a "golden girl" seems natural considering that her name also gives us images of yellow hues. The word jingle makes me think of coins in someone's pocket. As long as she has an infinite amount of money, she will be powerful because her voice will sustain the musicality.
If readers weren't yet sure whether or not Gatsby is in love with Daisy, her money, or the idea of Daisy, describing her voice as "full of money" may be an indicator of Gatsby's true desires.