There's a low rumble at idle, and above 4, 000 rpm this slowly rises in urgency.

FORBES: Test Drives

It began as a low rumble, I thought it was a train or large machine on the road at first, but when the whole house began to shake I realised it could only be an earthquake or perhaps a large plane crash.

BBC: Cumbria quake: Your comments

The applause started as a low rumble and then it became something wilder and appreciative, and then there he was, Ogden himself, all 6 feet 9 of him, unmistakable, wide as a big screen, walking on the floor, dressed in a sharp black shirt.

WSJ: Super Bowl: The Night (Half) the Lights Went Out

In the sudden darkness, he heard a low, heavy sound, like breath, all around him, a single, deep rumble that strung his veins together and spread through his skull.

NEWYORKER: The Tiger��s Wife