The engine whine died to a dull hum, and the silence of the bridge chewed at the captain.

The dull hum of today's computers falls way short in providing protective white noise.

And then he found it-a place that did not vibrate under his hands with the same dull hum as the other spots on the barrel.

First there was just a dull hum, an electricity in the dark cold air of the underground passage.

He stood listening outside a school to the dull hum of education.

I heard the voices, a dull hum rising.

The transmitter and receiver were still on; each person, entering, heard the dull, low hum.

A dull hum suffused the room, and the five people in the chamber evaporated into shafts of light.

The dull hum of the transformer changed pitch; cycled down even lower.

Then the dull hum would come again.