Dialogue - The Voice
No strict dialogue, but he addresses Emma by using 2nd person pronouns of "you".
He also tries to interact with her through interrogatives like "Can it be you that I hear?" and imperatives like "Let me view you, then."
If you get a question on dialogue and are stuck on what to pick, this poem is risky, because it doesn't feature strict dialogue, yet you may feel like you have to, because other poems like Neutral Tones and The Haunter include strictly no dialogue.
Dialogue - Under the Waterfall
We only realise the narrator is speaking to someone after the interjection from character 2's interrogatives: "Why is this...?" It could be that the second character is a child, which would emphasise that the lovers have moved on.
Also, the narrator's discourse marker of "Well," indicates a light-hearted story-telling manner, showing that the poem is transcendent.
Dialogue - The Haunter
This poem is purely a monologue and there is no real dialogue.
However, the rhetorical question: "I, too, alertly go?" shows a sense of worry and uncertainty.
And she also uses a discourse marker: "Yes," which shows she is agreeing with herself.
Much like The Voice, if you're presented with a question about dialogue, I wouldn't choose this poem, because it's too tricky to argue that there is any real dialogue.
Dialogue - Neutral Tones
NO DIALOGUE - don't choose this poem.
Dialogue - Convergence of the Twain
The only dialogue we have in this poem is the fishes' dialogue, which is ironic because this is obviously primarily a form a personification.
They "query: What does this vaingloriousness down here?" which emphasises that the man-made ship doesn't belong int he sea, and because of its tragic end caused by the vanity of humans, it has no purpose.