While playing, my child makes sounds like "ah" and "ooh," but I don't hear sounds like "ma" or "ba" yet. How should I interact with them at home?

First, imitate the sounds they're already making and enjoy the back-and-forth of "when I make a sound, the other person responds." You can also slowly show sounds like "pa-pa-pa" or "ma-ma-ma" where your child can see your face, but there's no need to keep repeating them trying to make your child say them. Watch to see whether the variety of sounds and the back-and-forth are increasing. If you're also concerned about how they respond to their name or to sounds around them, you can talk it over, including their hearing, at a checkup or with your pediatrician.