This can be very frustrating when a learner or group of learners do not listen. I teach Post 16 learners and don't generally get to many issues as they have chosen that specific course. However I have taught in a secondary school where discipline was very strict but often challenged by learners.
Changing your tone of voice can be very effective, Lowering it or raising it will signal to learners that it's time to pay attention. I have found that sometimes learners may not listen because they simply do not understand the task set. Incorporating quality and diversity is essential and from my experience has effected learners. We can make sure that our lessons accommodate all learners, however sometimes learners may still not understand.
This is very Broard so Could you possibly give me an example of the issue so that I could comment more effectivley.