The other helicopter had been so close she hadn't noticed the sound of Ken's approach.

He heard them depart at the sound of his approach.

The sound of its owner's approach so silent he had been taken by surprise.

Her back was turned to him and the soft sand covered the sound of his approach.

He looked up at the sound of our approach and tried to give us a smile.

Listening around the bend, he could hear the sounds of their approach.

He scrambled to his feet at the sound of their approach.

The sound of his approach was lost in its shriek.

He turned at the sound of her approach, and their eyes met, then dropped quickly away.

The music had covered the sound of his approach.