For babies, language comes through two pathways, both hearing and seeing, for the hearing child they listen to streams of speech and sounds and evenutally mimics what they hear. In Deaf children who have parents who sing, instead of listening to streams of sounds, they see streams of signs, which ultimately leads to the formation of language by the age of 4. However, language development can be blocked if they can not acquire spoken language and are not exposed to sign language early enough.