They may well need a speech consultant eventually, but not now. What they need now is for you to talk to them frequently, to read to them, to respond when they make any effort to talk. Find time to do something with each one individually; don’t fall into the pattern of always speaking to the two of them together. Try not to frustrate them too much by demanding too often that they tell you, rather than show you, what they want.
I’m going to suggest that you check out an article I wrote for this web site a few months ago called “From Babbling to Talking.” Just search for articles under the "Language & Learning" category and you can find it. It has many good suggestions you can use to help your children learn to talk.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.