His voice had hardened and he didn't look her in the eyes.

His voice had hardened as he turned back to her.

His voice hardened a little to take on an edge.

Something of the thought must have shown on his face, for the voice hardened slightly.

Especially," and his voice hardened, since no one back on Earth cares enough to find out what's happened to us."

His voice hardened, and an edge of cold fury showed through.

Now he was fully awake and his voice had hardened.

"I think I'd like to know what this is about," she said, her voice hardening.

The Warder did not move, and her voice hardened again.

Then his voice hardened, and for a moment he was like the Toranaga of old.