[She smiles gently, looking sympathetic but not annoyed at their trouble responding.]

I take it you have difficulty speaking? It's all right, you're far from the only one I know who does. I've been learning how to speak in hands, if that helps?

[She punctuates her spoken reply with one pair of hands repeating the same sentiment in sign- she suspects they'd have tried this method already if they could, but it seemed remiss not to at least mention the possibility.]