What is the Relationship between Language and Speech?

We have already indicated that sign languages provide evidence that language and speech are separate and that it is possible to learn and to use a human language, with all the complexity and richness of any other language, without the use of speech. A related question is: Can a hearing individual learn an oral language without being able to speak it? There is evidence in the affirmative from individuals who, for various physical reasons, cannot develop speech. In some cases, damage to the vocal apparatus can cause this dysfunction; in others, it may be more general motor impairment, as in the case of individuals with severe cerebral palsy (Bishop 1993). Can children learn oral language without being able to babble and progress naturally through the other stages of language development? The evidence suggests that they can. Some infants must have tracheostomies, procedures that insert a tube into the windpipe, to allow them to breathe. The tube may remain in place for months, or even years, preventing them from making sounds with their vocal cords. Studies of such children after reversal of their tracheostomies indicate that they develop normal language skills, with no lasting effects from the tracheostomies. So, at least we know that there is no permanent impediment to language development if speech is delayed. Even more significant, we now have considerable evidence that individuals with permanent motor impairments that never allow them to talk still develop language, sometimes with very high degrees of sophistication. One noteworthy example is the case of Richard Boydell (Bishop 1993, p. 228). Boydell had cerebral palsy, which prevented him from speaking. At the age of thirty, he was given a foot-operated typewriter, and it is claimed that nine days later he wrote a well-written letter to the manufacturer suggesting changes in the design of the typewriter. With more sophisticated use of modern computer-driven equipment, there are more recent accounts of people without the capacity for speech who read and write English with skill.