Her voice altered, as if she'd read something in the helmsman's body stance.

The image's voice altered slightly, into an almost hostile, demanding tone.

Then the fight began; the voices altered; and I woke from my dream.

Finally, a voice that had been altered with an electronic synthesizer.

He knew what she meant and why her voice had suddenly altered.

His voice altered to a tongue which she did not understand.

Poirot's voice altered a little, as it always did when speaking of this particular individual.

Joanna doesn't change the lyrics, but you might find that her voice alters the story line.

The dragon's voice had altered, rolled on the air like thunder.

As if a mere voice could alter the way a Star moved.