The speaker in Butler's "The Lake Isle of Innisfree" (1892) is clearly in the midst of an urban environment as he thinks about Innisfree:
While I stand on the roadway, or on the pavements gray,/I hear it in the deep heart's core. (ll. 11-12)
The tone expresses the speaker's regret that he is so far from where his heart tells him he should be, and it's equally obvious that he has spent much of his time not at Innisfree but on the "pavements gray." Further, his use of "pavements gray" tells us that the urban environment in which he finds himself is exactly the opposite of the natural world he desires to return to.
What seems to be most important to the speaker is not just being back in nature but obtaining something that is not available to him while his is in the city:
And I shall have some peace there, for peace comes dropping slow,/Dropping from the veils of the morning to where the cricket sings. . . . (ll. 5-6)
Every natural image the speaker uses in this poem is meant to point up that nature and peace are inseparable, and that those two vastly important things are available to him at Innisfree rather than in the city. And the problem for the speaker is not just that he is in the city as opposed to being in nature--he is currently in a place (the city) that his inner being finds completely wrong. The city, in other words, contains nothing that he desires, and his heart feels the absence of peace.
As the speaker stands on the pavement, he feels isolated and detached from the natural world where he longs to be, so much so that, as he envisions the ideal natural life at Innisfree, he hears nature resonate deeply in his heart, his inner being, not through his ears.