By about 20 weeks of pregnancy, baby’s inner ear is fully developed. In other words, baby was born with a sense of hearing. So if you think your newborn isn’t paying attention to what you’re saying, think again. All that changes as baby grows is her reaction to the sounds she hears (not to mention her ability to understand them). By two months, baby will be able to recognize familiar voices; by four months, she’ll try to investigate where they’re coming from; and by six months, she’ll most likely start imitating what she hears (so watch those four-letter words).