She has a very loud/quiet/soft voice.
a clear/deep voice
You could tell from her voice that she wasn't pleased.
She lowered her voice to a whisper.
Could you please keep your voices down?
Her voice is so clear and she has the nicest eyes which I've ever seen. (Preliminary English Test; B1; German)
She had a bad cold and was losing her voice.
I immediately became agitated and at the precise moment of my speech I lost my voice completely. (First Certificate in English; B2; Italian)
He never raised his voice at the children.
Not every au-pair family is pleasant. And believe me, mine was giving me hell on earth. [...] After I returned home I took some time to learn not to freak out when someone raised his voice and eventually I started to see my time in Germany as a great [lesson in] life. (Certificate in Advanced English; C1; Czech)
He has voiced concern about the new proposals.
And in the end they voiced their wishes to re-unif[y] Germany. (Certificate of Proficiency in English; C2; German)