These people speak for themselves, uttering words they formulated themselves for the audience before them, and the audience isn't expected to interrupt.

这些人是在为自己说话，为面前的观众陈述自己的观点，观众不需要打断他们。

youdao

Facts speak for themselves.

事实本身就是很好的说明。

youdao

Let the facts speak for themselves.

还是让事实说话吧。

《新英汉大辞典》

"Our motives were the right ones. Other people must speak for themselves.

VOA: standard.2009.08.21

Rather than letting otherwise substantial facts speak for themselves, Karlan and Appel over qualify their evidence.

FORBES: Book Review: Making Poverty History

The titles of "Daddy Needs a Drink" and "You and Your Crystal Meth" speak for themselves.

NPR: Drive-By Truckers: New, 'Brighter' Songs

Like people everywhere, they have the universal right to think and speak for themselves.

WHITEHOUSE: On Nowruz, President Obama Speaks to the Iranian People (Arabic) | The White House