The University of Auckland Clinics

Understanding hearing loss

The ear’s hearing system comprises three parts: the outer ear; the middle ear; and the inner ear. Damage or impairment to any one of these parts can compromise a person’s hearing.

The outer ear (which includes the ear canal) collects sound and sends it to the middle ear. Problems with the outer ear can lead to what’s known as conductive hearing loss.

Problems with the middle ear (which includes the eardrum and the tiny middle ear bones) can also cause conductive hearing loss.

Inside the inner ear are a number of fluid-filled cavities. The inner ear also carries an organ devoted to the body’s sense of balance: the snail-shaped cochlea.

The cochlea is covered in sensory “hair” cells. These tiny cells and their nerve fibres can be damaged or destroyed by many things, including noise and the ageing process.

Symptoms of “hair” cell damage include:

  • ringing, whistling, hissing or other sounds inside the ears or the head (known as tinnitus)
  • low tolerance to loud sounds (known as recruitment)
  • extreme intolerance to everyday sounds (known as hyperacusis)
  • hearing sounds with lack of clarity (known as distortion)
  • hearing sounds at the wrong pitch (known as diplacusis)

Audiologists map the individual’s hearing loss at different frequencies to build an overall picture of the person’s hearing. From there, they can advise clients about treatments and hearing devices.

Treatments for hearing loss