The common claim the that the stories are remarkable for their even tone seems to me to miss the point.

"Well, it looks awfully good," she said, marveling at the even tone of her voice.

His even tone cracked into a sound like a sob.

Poms frowned, but his voice kept to its even tone.

"I think we found the nukes," he said, surprised at the even tone of his voice.

I spoke in the even tone of an independent auditor at a stockholders' meeting.

Batman marveled at the even tone of the Admiral's voice.

"I shall be here a while longer," he said, in the even tone of Cranston.

"Your grace," he said in his even tone, "it is not a matter for jesting."

His muscles had the even tone of artificial exercise.