Callie stated quietly, the low drone of her voice the only sound for miles.

Above them, the wind howled across the opening with a low drone, like someone blowing over the mouth of a bottle.

Finally there was Kidd, who smiled and spoke in his customary low drone that sounds as if he is just getting over a cold.

A quiet mechanical click, and then a steady low drone.

The low drone of the hives could be heard and he felt his eyes prickle at the sound.

They heard a low drone, not of conversation, but of a male voice singing.

The low drone of their voices came to Martine now through the traffic noises.

A low drone rolled over the horizon and grew louder.

She also heard a low drone from the other direction, growing higher in pitch the longer she listened.

A new and deeper note entered the low drone in the air.