A hearing impairment or deafness's a full or partial decrease in the ability to detect or understand sounds. Caused by a wide range of biological and environmental factors, loss of hearing can happen to any organism that perceives sound. "Hearing impaired"'s often used to refer to those who're deaf, although the term's no longer politically correct. In Deaf culture, they prefer the terms Deaf and Hard of Hearing. Sound waves vary in amplitude and in frequency. Amplitude's the sound wave's peak… (More on Deafness)