Hearing loss causes, types and signs

How do we hear?

The pathway of sound, which allows us to hear, is an interesting one. Sound waves move from the external environment, through the ear system, to the brain where it is processed and a response is initiated. The sound waves travel through the medium of air from the outer ear. In doing so, it creates a vibration of the eardrum. This vibration travels from the eardrum to the middle ear bones and then moves into the inner ear where it makes contact with the cochlear (organ of hearing) and the inner ear fluid. At this point, the energy of the sound wave is transmitted through the auditory nerve to the brain, where sound is processed.

What causes hearing loss?

There are various causes for hearing loss. Some of the most common include: hearing loss resulting from ear infections, the natural ageing process and excessive exposure to loud sounds. The audiologist will be able to take a detailed case history from you and diagnose which part of the auditory system has been affected. This will provide information regarding the cause of hearing loss. In some cases, the cause of hearing loss may be unknown and require further investigation.


Types of hearing loss

There are three main types of hearing loss.

Conductive hearing loss- In this type of hearing loss only the outer and/or middle ear has been negatively impacted. An example of this is a hearing loss as a result of an ear infection

Sensorineural hearing loss- In this type of hearing loss only the inner ear has been negatively impacted. This may be the cochlear (organ of hearing) or the auditory nerve. An example of this is a noise induced hearing loss or age-related hearing loss.

Mixed hearing loss- This is a combination of a conductive and sensorineural hearing loss, where the outer and/or middle ear and the inner ear has been affected. An example of this is a traumatic hearing loss from in a car accident or a genetic malformation of the ear.

Seeing the signs

There are many signs of hearing loss. These are some of the most common:

  • needing to increase the volume of the television, radio etc.to levels which become uncomfortably loud for other people.
  • difficulty hearing without lipreading even in quiet environments.
  • often asking people to speak louder and more clearly.
  • speech sounds muffled and it is difficult to tell what is being said.
  • great difficulty conversing and understanding speech when background noise is present.
  • difficulty hearing and the presence of a ringing sound in the ear.
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