Blue tit nestlings not chirping

I have got Blue tits nesting in my garden box for almost two weeks now. 

Parents in and out busy feeding constantly. I have ensured they have plenty of mealworms by making a sectioned off area to ensure they have sufficient food as the Starlings and Jackdaws gorge. I have ensured they get plenty too. 

However there is no chirping coning from the nestbox, is this normal or do they not need to beg for food as there is a ready supply coming and they are well fed, full and happy? 

Thank you.