The horse creates a vibrating sound with his mouth closed, from his vocal cords.

马闭上嘴从声带发出的振动的声音。

youdao

You could say you got the information straight from the horse's mouth.

VOA: special.2009.07.12

Sometimes you get information straight from the horse's mouth.

VOA: special.2009.07.12

The evidence to the contrary is clear, and straight from the horse's mouth, with organisations like the Association of British Pharmaceutical Industry and the Wellcome Trust saying that it is public investment which incentivises their own operations.

BBC: Viewpoint: Science 'critical for UK economic future'

And so to Wednesday , where the EFRA Committee (at 2.45pm) takes evidence from the horse's mouth, (sorry), from the government, Tesco, Iceland and the Food Standards Agency on the contamination of beef products.

BBC: Week ahead in committees

Firsthand sources: The best way to ensure information is correct is to take it from the horse's mouth.

CNN: Locating sources and fact-checking