How does the speaker describe his loneliness in "Acquainted with the Night"?

In Robert Frost's sonnet "Acquainted with the Night," the speaker walks out alone during the nighttime. Since he says he has been "one acquainted with the night," we can assume he has done this relatively often. The poem has a haunting feeling of loneliness because the speaker doesn't interact with any other person in the poem. Although he passes the "watchman on his beat," he doesn't greet him. In fact, he drops his eyes so he won't have to exchange words. This doesn't mean he doesn't care about people. He looks "down the saddest city lane," presumably with compassion for the residents there.
The lines of the poem that best express the speaker's loneliness are lines 7–10, which describe how the speaker hears an "interrupted cry" wafting toward him. He stops walking to pay attention to it, and we wonder if he is longing to hear his own name since he says, "but not to call me back or say good-bye." That desire for someone to make contact, to ask for his return, or even to bid farewell goes unmet. That is a powerful description of loneliness.
That the moon, "one luminary clock against the sky," cannot tell him the time is right for his desire to be fulfilled, adds additional poignancy. Indeed, being "acquainted with the night" is an interesting way to describe and characterize the sadness and longing that comes with isolation.