When your son was a baby, who took care of him?

Do the care-giver have problem "把k,g,t等都发成d"，"ch,zh,sh也发不好"? Or does the dialect you use at home distinguish between k/g/t/d, ch/zh/sh? 听力检查 is very necessary. If hearing is OK, speech therapy will be the only way to improve. The earlier to start, the better.