The Vestibular Disorders Association site describes inner-ear balance disorders that leave people suffering from imbalance, dizziness, vision problems, and even nausea. This site holds abundant information on the causes and prevention of vestibular disorders.

http://www.teleport.com/~veda/

The causes of hearing loss and the advent of the hearing aid "digital age" are discussed in this Mayo Clinic Health Oasis article entitled Hearing Aids. Various hearing aid remedies are described.

http://www.mayohealth.org/mayo/9807/htm/hear.htm