It is believed by some that cochlear implants for congenitally deaf children are most effective when implanted at a young age. However evidence shows that Deaf children who sign well do better academically. Thus specialists recommend that all Deaf children should learn sign language from birth. Deaf culture critics also point out that the cochlear implant and the subsequent therapy often become the focus of the child's identity at the expense of language acquisition and ease of communication in sign language and Deaf identity. They believe that measuring a child's success only by their mastery of speech will lead to a poor self-image as "disabled" (because the implants do not produce normal hearing) rather than having the healthy self-concept of a proudly Deaf person.