Hearing-impaired is a broad term that refers to varying degrees of hearing loss from partial to total deafness. The age of onset plays a crucial role in the development of language; persons with a prelingual hearing loss often have weaker oral communication skills than those whose loss occurred after speech development.  The causes and degrees of hearing loss vary across the deaf and hard of hearing community, as do methods of communication.  Hard of hearing refers to those individuals who may use speech, lip-reading and/or hearing aids to enhance oral communication.   Students who are deaf or hard of hearing may utilize a wide range of services depending on the language or communication system they use.