In some cases, the loss is extremely sudden and can be traced to specific diseases, such as meningitis, or to ototoxic medications, such as Gentamicin. In both cases, the final degree of loss varies. Some experience only partial loss, while others become profoundly deaf. Hearing aids and cochlear implants may be used to regain a sense of hearing, with different people experiencing differing degrees of success. It is possible that the affected person may need to rely on speechreading and/or sign language for communication. In most cases the loss is a long term degradation in hearing loss. Discrediting earlier notions of presbycusis, Rosen demonstrated that long term hearing loss is usually the product of chronic exposure to environmental noise in industrialized countries (Rosen, 1965). The U.S. Environmental Protection Agency has asserted the same sentiment and testified before the U.S. Congress that approximately 34 million Americans are exposed to noise pollution levels (mostly from roadway and aircraft noise) that expose humans to noise health effects including the risk of hearing loss (EPA, 1972). Certain genetic conditions can also lead to<unk> . In contrast to genetic causes of pre-lingual<unk> , which are frequently autosomal recessive, genetic causes of<unk>  tend to be autosomal dominant.
Post-lingual deafness
Nonsyndromic deafness
Cortical deafness
Hearing loss with craniofacial syndromes
Optic nerve hypoplasia
Septo-optic dysplasia
Prelingual deafness
Vibroacoustic disease