The tone of Grace's voice had become suddenly more up-beat.

He had been speaking in an almost conversational voice, but now his tone became louder.

"I don't believe in color lines," he said, his tone becoming lighter again.

You know what I mean, she said, her tone becoming sharper.

How could a tone become a picture and light become a noise?

His tone had suddenly become more serious, as though he regretted bringing up the subject.

Polly was shocked at how bitter Jack's tone had become.

She looked at him curiously; his tone had become hostile, suddenly.

The general irritable tone in the family will also reduce and become more relaxed.

Over the years the tone of the photographs has become darker and more complex.