on Jane Friedman site:

One of the most frequent pieces of advice authors hear from agents and editors in making their work stand out is that it needs to have voice: strong voice, a unique voice, a compelling voice—or even just be “voicey.”

Voice is arguably among the most important factors in catching the attention of agents, editors, and readers. As literary agent Amy Collins of Talcott Notch says, “Manuscripts may have crisp, engaging dialogue, glorious descriptive scenes, and a great plot… But none of that matters if the tone of the writing is bland or the voice is not unique.”

This is where authors may feel a bit flummoxed. We know voice matters—enormously—in setting our stories apart in a crowded market. But what the hell is it, and what makes it powerful or intriguing or distinct? And if it’s too strong or distinctive, might it not draw attention to itself—like Fergie’s rendition of the National Anthem?