He tends to use a lot of slang expressions that I've never heard before.

他往往用许多我以前从未听说过的俚语。

《牛津词典》

It is that crying I heard before.

这是我之前听到的哭声。

youdao

We heard those songs we have heard before.

我们听到了之前听过的歌。

youdao

I just thought it was most amazing sounding thing. It sounded like nothing I'd ever heard before,I guess."

VOA: standard.2010.07.01

Programs that can produce music that have-- that we recognize as music, that have melodic structure and develop themes, resolve, music that nobody's heard before.

这些程序可以生成,我们认可的音乐,这些音乐具有旋律形态和递进的主题,有转为和音的章节,而且从未有人听到过这些音乐

耶鲁公开课 - 死亡课程节选

So, we could create and understand sentences that we never heard before.

因此,我们能够创造和理解,那些我们未曾听过的句子

耶鲁公开课 - 心理学导论课程节选

Words I had never heard before had a significance for him, and a private satisfaction.

NEWYORKER: Mr. Bones

But they have mostly been heard before, and Mr Maliki's government has failed to achieve them.

ECONOMIST: George Bush announces a last push for ��victory��

It's a promise Greeks have heard before, and many here don't believe it'll be kept.

BBC: Greek finance minister eyes 2014 recovery for economy