General:
* Disruptor
* Interrupter
* Jeerer
* Mocker
* Yeller
* Shouter
* Crier
* Bawler
More specific:
* heckler (this word is quite specific and often used in the context of public events)
* heckler (implies a more aggressive and hostile tone)
* heckler (more focused on verbal abuse and insults)
* heckler (implies a less aggressive, but still disruptive, behavior)
* heckler (implies someone trying to derail a speaker with irrelevant points)
Other possibilities:
* heckler (more formal, often used in academic settings)
* heckler (implies a more organized group of people trying to disrupt an event)
* heckler (used to describe someone who constantly interrupts or criticizes, not just at public events)
Remember that the best synonym will depend on the specific situation and the intended meaning.