I've reassured myself until now with the fact that he seems to understand most of what we say to him (and told myself that the other times he just doesn't want to hear) and that he interacts very well socially - plays with other children, shares, joins in games etc. BUT he still doesn't really talk - his vocabulary is limited to "dop" ("stop" - only when playing Musical Statues with his sister), "poon" for "spoon" occasionally, "dox" for "socks" and "book".
He says "da" and "der" a lot and very emphatically. He thinks he's talking. And he sings to himself fairly tunefully. But he doesn't say "mama" or make any words/sounds that begin with sounds other than "ba" or "da".
Is it worth, do you think, getting his hearing checked? He had measles a few months ago and was quite poorly - am wondering if perhaps there might be a problem there. Has never really occurred to me before now. I don't want the doctor to laugh in my face and tell me dox/poon/dop/book is a perfectly adequate vocabulary for an 18 month old and to stop wasting her time.