Your ears are remarkable. They each consist of three parts - the outer ear, the middle ear, and the inner ear.
The outer ear serves to collect and channel sound to the middle ear. The middle ear transmits sound waves striking the ear drum via three tiny bones into vibrations within the inner ear.
The inner ear then changes these vibrations into nerve impulses which are sent to the brain and detected as sounds we can understand. In addition the inner ear has an important role in our sense of balance.
The ear can hear a very wide range of sounds. It is most sensitive to frequencies between 500Hz and 4000Hz, which corresponds almost exactly to the speech band.
Should our hearing decline we may become hard of hearing or deaf. There are 9 million affected people in the UK- most of these will have developed the hearing loss as they got older.
Around the age of 50 the proportion of deaf people begins to increase sharply and 55% of people over 60 are deaf or hard of hearing.
For more information about hearing problems and the hearing aids that can be provided to help take a look at the website of the R.N.I.D. (The Royal National Institute for Deaf people): http://www.rnid.org.uk/.