Our group is studying the genetics of vocal communication in mammals, as a way to understand the evolution and biological basis of human speech and language. (mpi.nl)
Limited research suggests that baby sign language might give a typically developing child a way to communicate several months earlier than those who only use vocal communication. (mayoclinic.org)
As you won't be relying on vocal communication, you should encourage the most interesting and entertaining visual interaction as possible. (blog.behappy2day.com)