"upbeat voice" is correct and can be used in written English.
You can use it to describe someone's manner of speaking that is cheerful and enthusiastic. For example, "The teacher greeted the students with an upbeat voice."
So why is there a note of regret in Grasar's otherwise warm, upbeat voice?
"But you get used to it," he says, in the upbeat voice of a person delivering a positive TripAdvisor review.
Or, most tantalizingly, who would have thought the most upbeat voice in American politics, online or off, would be the mayor of Newark?
His job was to buoy up the audience into a frenzy of excitement, and he did have an upbeat voice, but the things he said were terribly miserable.
The doctor pressed ahead, in a cheerful, upbeat voice, tinged with regret, saying that the staff had to decide what was better for Mr. Oltzik in the long run and wanted the family's opinion.
"Oh no," she replied in her typical upbeat voice.
So keep the "marijuana use will turn you into a sloth" stuff, but get a more upbeat voice-over artist to underscore that this is a transformation that's actually for the best.
"I'll be gone for a moment," she said to the infant in an upbeat, gentle voice.
The lead singer, Owen Strathern, looks a lot like a young version of Echo and the Bunnymen's Ian McCulloch and has an upbeat tenor voice heard on songs like "The Age That You Start Losing Friends".
Yet even when he is singing an upbeat tune, his voice is suffused with a certain melancholy.
The commissioner, in an upbeat and commanding voice, spoke proudly of the improvements brought by her signature project in New York: bicycle lanes that, she said, slowed down cars, encouraged more cycling and reduced injuries to pedestrians.
