talk to a brick wall

If talking to someone is like talking to a brick wall, the person you are speaking to does not listen.

如果和某人说话就像对着一堵砖墙说话，那么你说话的人是不会听的。

A: I keep telling the staff not to put food in that bin, but they don't listen.

我一直跟员工们说别往那个垃圾桶里扔食物，但是他们就是不听。

B: Yes, I know. It's like talking to a brick wall.

是的，我知道，就好像对牛弹琴一样

I've tried to discuss my feelings with her, but it's like talking to a brick wall.

我曾经试着和她谈我的感受，但好像是对牛弹琴。