She followed, tracking him by the sound of his voice as he called out to people to make way.

"In a lot of places, the road is close enough and you can track better by vehicle."

In the dark, the Guardian could only track him by sound.

We have tracked every computer entry by the person in question.

"They would track us by the sound," I told him.

He had learned that you could often track street crime by sports teams and their activities.

They aren't supposed to know that we track them by their uniforms.

The idea was to surprise Russian forces who might otherwise track them by their radio calls.

Some can track by scent or sound, but they're said to be lazy.

You told me he can track us by our wake.