No matter how firm she tried to be, her voice still wavered.

My voice wavered a little on that last word, but didn't break.

Her voice wavered, as if she might begin to cry again.

Her voice wavered on the last word, as if the pain of that meeting was still fresh.

Her voice wavered, but then she caught it, and went on.

Again her voice wavered and she had to make a visible effort to control herself.

My voice wavered as I tried to suck in air and move at the same time.

She tried to snap it out, but her voice wavered.

His voice wavered, and he struggled to get it under control.

Her voice did not waver and for that she was very glad.