As I watched, the hatch slipped open with a mechanical hum audible even at that remove.

She was sinking, but the next mechanical hum had her pulling back.

There was a mechanical hum as the power units started.

A few more minutes, and, with a buzzing mechanical hum, the gates slowly opened.

From somewhere below him came a faint mechanical hum, a tiny vibration-another automated system, probably.

A mechanical hum rose, a vibration more felt than heard.

The door opened with a mechanical hum, and for a moment Kira could not make sense of the scene that lay before her.

He inserted the key, turned it on and jerked at the mechanical hum the car emitted.

She thought she heard a low, mechanical hum coming from the interior of the door.

In the silence, Jeremy could hear the steady, mechanical hum of the ultrasound machine.