(b) An oral interpreter shall be provided upon the request of a deaf person entitled to an interpreter under this article, but who does not communicate in sign language. The right of a deaf person to an interpreter may not be waived except by a deaf person who does not use sign language and who initiates the request for waiver in writing. The waiver is subject to approval of legal counsel for the deaf person, if any, and is subject to approval of the appointing authority.