I'm glad to see you trying your hand at this, Simon. I've attempted it myself—it's a hard one, and probably best enjoyed (in English) in something like the way Weinberger and Paz present it. No translation is going to get everything, so I'm going to try not to hold you to that standard. Still, I think there are a few issues worth thinking about.
First, I question the choice of "visible" and "audibly" in the first two lines. The Chinese gives you a scene, I think, tells you what is there and how it is experienced. But you've chosen dispositional words, which add possibilities to the scene. Also, while I suppose something could echo inaudibly, there's more than a whiff of the redundant about "echoes audibly", in contrast to the strict economy of the original.
Second, "human conversation" seems like an overinterpretation. The Chinese says that there is the sound of a person's voice (or people's voices), but it's not specified that it's conversation. It's unavoidable that, in English, you're going to limit the possibilities the Chinese leaves open, but this does so a bit too much for my taste. (I also don't love that "ren" changes from "person" to "human" and from a noun to an adjective between the two lines.)
Third, I think "pierces" is far too violent a word for the mood of this poem. It is a peaceful scene; nothing is piercing anything.
I hope these thoughts are helpful for you.