The phrase "a tentative voice" is correct and usable in written English.
It can be used to describe a manner of speaking that is uncertain or hesitant, often indicating a lack of confidence or firmness.
Example: "She spoke in a tentative voice, unsure if her ideas would be well received by the group."
Alternatives: "an uncertain tone" or "a hesitant voice."
In a quiet, tentative voice, she explained to me that there was, in fact, an objective, scientific way to test me for environmental illness; she could do it right then and there.
And so the other night when my teenage daughter briefly turned her eyes away from "The Simpsons" to ask in a curiously tentative voice if the Troubles were coming back, I was able to say, "No, no they're not".
Generally, Echo users seem to buy it as a toy or out of curiosity and slowly adopt it into their lives, one tentative voice command at a time.
Ms. Parsons does her best to give distinctions to such musical bromides, despite a tentative singing voice.
Her main qualifications, other than the fact that no one else wants the job, are an innate, unsmiling bossiness, neat handwriting and her ability to perform, in a tentative, quavering voice, one song about Chairman Mao.
A rhino calf was mewing in the pan next to its mother, a tentative little voice that now made me think of scampering little newborn elephant steps and Wynona's steadying trunk, reminding me that birth and strife are inextricably linked in the natural order of things.
A few months ago Kyle Fischer released "Open Ground" (Polyvinyl), a collection of subdued songs with sharp lyrics, although his tentative voice seemed calculated to drive away all but the most tolerant listeners.
At the beginning there was barely any music, just Mr. Banhart's tentative voice: "My friend has my favorite teeth/They bend backwards when she breathes/And it whistles".
As we left the intimate cocoon of the pub, my bouncy excitement became more of a trudge as, heart in mouth, I babbled and swore, and panicked that I couldn't do it, terrified that stage fright and nerves would overtake me, and that my tentative voice would abandon me altogether.
You could say she is to garage and dubstep what SZA, Kelela, Jhené Aiko et al are to Aaliyah and Cassie, but actually the first few times we heard the tracks on her forthcoming EP2 we just assumed she was American (her tentative voice has been compared to Janet Jackson's at its most girly).
