John's slight speech impediment made it difficult for his mother to understand him.

约翰轻微的口吃使他母亲难以听懂他。

《柯林斯英汉双解大词典》

It's difficult to understand him because he has a speech impediment.

他的话很难听懂，因为他讲话口吃。

youdao

Off the court though, he is seen as dense and dull on account of his speech impediment.

在场上，由于他的言语障碍，他被视为密集和沉闷。

youdao

Researchers say the speech impediment appears to stem from a defectin the gene that regulates the way brain cells break down and recycle waste products.

VOA: standard.2010.02.11

The abnormal gene also was found in 77 unrelated Pakistanis with the speech impediment.

VOA: standard.2010.02.11

Seventy-two years ago tomorrow, a chubby, stoop-shouldered, funny faced man with a speech impediment took a new job.

FORBES: Connect

While the newspaper mockery is not of a genuine speech impediment, for some there's a sense that it might encourage that type of behaviour.

BBC: Roy Hodgson: Is it wrong to mock the way he speaks?

The biggest impediment to this movie is Sandler's speech.

CNN: Review: Sandler should've punted 'Waterboy'