Our visitor's voice sank lower, and she leaned forward a little.

Her voice had sunk to a concerned whisper by the end.

His rich voice sank into me on waves of sympathy.

His voice sank so low that she could barely hear it.

However, their voices had sunk back down, and now she rested easily once more.

His voice sank to a whisper, 'You're doing what you know is right.

Her voice had been sinking, and this last was barely audible.

The man's voice sank lower; it carried a note of desperation.

On the other side of the door the voices sank very low.

He thought for a while, and his voice sank to a whisper.