Wanted to pass this along: http://www.csun.edu/~sp20558/dis/deaf.html
Rarely is a person completely deaf, and a hearing loss could fall anywhere along the continuum from totally deaf to hearing. The amount of usable (or residual) hearing varies greatly from person to person. Depending upon the type of loss, the person may or may not benefit from the amplification that a hearing aid provides. Hearing aids only amplify sound, they do not make sound clearer. The severity of a person’s hearing loss could be different at various frequencies. Therefore, ability to hear different voices will vary depending on a number of factors, including the pitch of the voice. Also, it is important to note that a person’s ability to hear a voice is different than the ability to discriminate between sounds and to understand speech.
The life activity most affected by hearing loss is communication. Colleagues and friends must be versatile in finding an effective communication method. Pen and paper are handy communication devices in some situations.
Though not effective for all people who are hearing impaired, knowing some sign language and fingerspelling is helpful. Learn some elementary or survival signs from colleagues, coworkers, or managers who are deaf or hard of hearing.
People who are deaf or hard of hearing, like people who are hearing, have different education levels. Knowledge of English grammar, syntax, and spelling varies from individual to individual. A person who uses American Sign Language (ASL) as their primary language of communication may or may not be proficient in using standard English. For the most part, English is an oral/aural language designed to be spoken and heard. Therefore, it is quite challenging to learn and understand English when you can not hear, especially when it varies so greatly from the structure and syntax of ASL. The person who is not proficient in English is not stupid or illiterate; he or she just uses a different language to communicate.
Not all hearing impaired people are good lip readers and lip reading skill has no correlation to a person¹s intelligence. Even good lip readers may miss many words. Keep in mind that only 25-30% of spoken English can be lip read. Not all deaf people know how to speak sign language, or choose to use sign language interpreters. Some prefer to communicate through lip reading and some prefer sign language.
The need for an interpreter depends on the situation and the people involved. Interpreters can be described as a communication link. A telephone, for example, is a communication link; it does not add information or alter the content of the message.
Deafness does not, in itself, affect intelligence.