He let the tone of his voice creep over into not completely benign mockery.

The distant tone that I'd come to know in the past month crept into his voice.

Not that he said anything directly, but a solemn tone crept into his voice.

A slight tone of humor crept into the captain's voice.

She checked herself there, conscious that a tone of bitterness had crept into her voice.

A tone of annoyance crept into the younger man's voice.

"Go on," the secretary insisted, a strident tone creeping into her voice.

But she has greater ambitions for her story, and soon a darker tone creeps in.

A defensive tone creeps into Volpe's account of his recent years.

The vice president is letting that supercilious tone creep back.