background noise
ground noise

From the sound of the background noise, Bill was in his car.

It's all background noise to the real work we have to do here.

By and large, it doesn't seem too different from the background noise when I was growing up.

There was a lot of background noise on the phone line too.

When you speak to a man by phone there is background noise.

The background noise was gone, and I knew that his car had stopped.

These background noises can still be heard on the record.

But a big city provides a high level of background noise at all hours, and it went well.

At this stage of things, it was just so much background noise.

"Wouldn't whatever sound it makes get lost in background noise?"