Hearing impairment is defined as a sensory deficiency that prevents a person from receiving sounds in their normal form. It can be caused by factors like rubella, heredity, prematurity, meningitis, ear infections, and environment. Students with hearing impairment may have difficulties with speech, language, reading comprehension, and processing oral information, especially in noisy settings. There are two main types of hearing loss - conductive, caused by outer/middle ear issues, and sensorineural, caused by inner ear or nerve problems. Assessments include audiology tests of brain waves, eardrum movement, and speech recognition. Educational approaches include oral communication focusing on speech, manual communication using signs, and total communication combining both.