Wolfe's voice sharpened a little, though perhaps only to my experienced ear.

She let her voice sharpen; he was keeping too much, lately, to himself.

Vaughn did not dare turn to look at her, but his voice sharpened.

He stopped short, and his voice sharpened into real anger.

His voice sharpened as he turned ; to face her.

Her voice sharpened as she drew close enough to see Min's face.

"Think you'd know better than to thank me by now," she said, and her voice sharpened.

"Tell me this then," I said, my voice sharpening a bit.

"I don't hear the sound well enough with this microphone," she finally announced, her voice sharpening.

Ryan asked, his voice sharpened by the sudden explosion of violence.