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Istituto Superiore di Sanità
EpiCentro - Epidemiology for public health
Epidemiology for public health - ISS

Hearing disorders vary in nature, but also in origin and severity.


Deafness is defined as complete loss of the ability to hear. The term “hearing impairment” is used to describe a partial loss of hearing, ranging from mild to moderate, severe and profound. If it occurs in only one ear, it is called “unilateral hearing loss”.


Clinically and audiometrically, hearing loss (also known as hypoacusis) can be divided into two broad groups, depending on what part of the hearing system is affected:

  • Conductive hearing loss: this condition results from disruption in the transmission of sound through the outer ear and middle ear, and can be caused by abnormalities, trauma and, above all, inflammation. It can be treated medically or surgically. The most common example is middle ear infection in children (otitis), which does not usually cause severe hearing loss (not greater than 50-55 dB)
  • Sensorineural hearing loss: it results from problems in the inner ear or auditory nerve that reduce perception of some frequencies and cause sounds to be distorted. Its most common causes include noise exposure and ageing. This condition is usually permanent and requires rehabilitation.

Publication date: 15 January 2021