my baby was started giving cooing sounds by 2 months suddenly she stopped for 1 week and again she gave cooing sounds and now she stopped giving cooing sounds for past 3 weeks.she is nearing her 5th month that is she is 3 month 27 days baby.she is keenly listening whenever I speak and also smiling , shouting ,getting excited but not involving in conversation by giving cooing sounds continuesly.she use to get fear if someone sneezes loudly...but why she has stopped giving cooing sounds... please guide me....