Deafness


Description:

Vaguely, deafness can be described as any level of hearing loss or impairment up to and including the inability to hear, which is considered to be completely deaf. A more specific and yet still broad description of deafness is that it is considered the inability of a person to hear, due to any of a multitude of reasons, at ANY volume despite the decibel magnitude. The phrase, "at any volume", is very important to include when discussing deafness because that is the specific element that qualifies this medical condition. Deafness is a common problem often caused by noise, age, disease, or any combination of these stimuli and is usually preceded by some form of hearing loss.. Hearing is a complex sense that involves both of the following: the ear's ability to detect (hear) and send auditory stimuli to the brain as electrical impulses to be interpreted and the brain's inability to process and interpret these electrical signals into sounds. There are three general types of hearing loss that may lead to deafness, as follow: conductive hearing loss (CHL), sensorineural hearing loss (SNHL), and mixed hearing loss.

Types of Hearing Loss:

As mentioned above, there are three types of hearing loss associated with deafness. These are detailed below.
  1. Conductive hearing loss.
  2. Sensorineural hearing loss.
  3. Mixed hearing loss.

Causes of Hearing Loss:

Noise:

The most common cause of hearing loss is prolonged exposure to loud sounds that cause stress to the ear. Noise-induced hearing loss is a preventable hearing disorder that affects people from any ages and demographics. Delicate and small hairs in the inner ear move in correlation with sound wave pressure. This causes the ear cells send an electrical signal through the auditory nerve to the brain, which interprets the signals as sounds.

Age:

Hearing loss is one of the most common conditions that affects older adults. Approximately 17 percent, or 36 million, of American adults report some degree of hearing loss. Hearing loss that occurs when aging is common. Presbycusis, or age-related hearing loss, is the effect of aging on hearing.

Disease:

Types of diseases that can cause deafness:
  • Meningitis
  • Measles
  • Presbycusis
  • Auditory nerve damage
  • Mumps

Cochlear Implants:

Cochlear implants are small electronic devices that can interpret the sense of sound for a person who is deaf or has a hearing problem. Cochlear implants bypass damaged portions of the ear and directly stimulate the auditory nerve. Signals generated by the implant are sent by way of the auditory nerve to the brain, which interprets the signals as sound.

ear_coch.jpg



International_Symbol_for_Deafness.jpg
The international symbol of deafness or hard of hearing




Citations:

http://nihseniorhealth.gov/hearingloss/hearinglossdefined/01.html
http://en.wikipedia.org/wiki/Noise-induced_hearing_loss
http://www.mayoclinic.com/health/hearing-loss/DS00172

Sources:

http://en.wikipedia.org/wiki/Noise-induced_hearing_loss
http://en.wikipedia.org/wiki/Deafness
http://nihseniorhealth.gov/hearingloss/hearinglossdefined/01.html
http://www.mayoclinic.com/health/hearing-loss/DS00172
http://www.nidcd.nih.gov/health/hearing/pages/coch.aspx