Doubt in being mindful when two tasks are going to happen?

When we are doing some work(eating food--**first task**).. we hear something important or some noise(**second task**), which might require us to pay attention to it(to **second task**).. (means if we want to be truly mindful, then how we have to deal with this situation) **NOTE:** In this case, the first task or work needs continuous attention stream of mindfulness from us.. and second one tries to hinder or abrupt first task's flow..