I could hear nothing but the background hum of the computer itself.

The only sound was the background hum of the instruments.

That background hum may soon be reduced to a whisper.

"It will just be the background hum of the book."

From the start, he wanted the "background hum" to catch in the reader's ear.

Instead, they create a sort of background hum, a sense that the person facing all these accusations must have done something wrong.

A moment later, another human voice rose above the background hum of the bridge's instruments.

It's like most of it is a continuous background hum.

The conversations going on around her turned to a meaningless background hum.

There was a different pitch to the quiet background hum inside her.