Rhythm is absolutely a part of the sound of your voice. I didn't mention it because people might say, "Define rhythm," and music teachers have told me nobody has ever come up with a definition of rhythm everyone agrees on (given that it goes beyond things like "beat" and "meter").

But I very much appreciate your mention of something that I pay attention to in my writing (for example, by trying to vary long and short sentences) and that others might also want to notice. Thank you!