When a poet recites poetry onstage, and the audience doesn't like his or her poetry, usually they just look bored and leave. When they do like it, they usually clap. You are describing a much livelier scene than we are used to seeing. However, theoretically, shouts of "bravo" in addition to applause are possible. I can't think of anything else to shout, except some general affirmative like "yeah." You must have great poetry or spoken-word sessions in Islamabad.