别说了。

Let's stop talking.

I'm tired of talking. (我都说累了。)

I don't want to talk anymore. (我不想说了。)

那事儿我听过了。

I've heard the story before. *用于对方重复说一件事时。

You've already told me.

I'm sick and tired of hearing that. (我耳朵都听出老茧了。) *sick and tired of...“对……腻透了”。

I've heard enough about it (already).*加already起强调作用。

I don't want to hear about it anymore. (我再也不想听那件事了。)

这件事别再说了。

Let's drop the subject. *drop除了“落下”之外，还表示“(问题、事件、话题等)完了、结束、停止”。

Let's drop it.

I don't want to talk about it anymore. (我再也不想说那件事了。)

别那么大声说。

Don't say it so loud.

Don't say that kind of thing so loudly. (那种事别那么大声嚷嚷。)

(Please) lower you voice. (小点儿声。)

例句：

Don't say it so loud. (别那么大声说。)

I thought you were hard of hearing. (我以为你没听见呢。)