The Collaborative International Dictionary of English v.0.48:
heckling \heckling\ n. [vb. n. from heckle[2].] Shouting in order to interrupt a speech with which the shouter disagrees. Syn: barracking. [WordNet 1.5]WordNet (r) 3.0 (2006):
heckling n 1: shouting to interrupt a speech with which you disagree [syn: heckling, barracking]