Sensorineural hearing loss
Some children have sensorineural hearing loss (SNHL) – this usually means that the cochlea (part of the inner ear) is not working effectively. Less often this means that the auditory nerve (the route from the inner ear to the brain) is not working effectively – this type of SNHL is called auditory neuropathy spectrum disorder (ANSD). SNHL is always permanent.
Conductive hearing loss
Some children have conductive hearing loss – this means that sound is unable to pass effectively through the outer and middle ear to the cochlea. Conductive hearing loss can be permanent or it can be temporary (for example, glue ear causes temporary hearing conductive hearing loss).
Mixed hearing loss
Some children have mixed hearing loss – this means that they have both SNHL and conductive hearing loss.
Severity of hearing loss
Hearing loss is measured in decibels (units of loudness).
Hearing loss can be mild (the least hearing loss), moderate, severe or profound (the greatest hearing loss). The severity of hearing loss typically varies depending on the pitch (also called frequency) of the sound. For this reason every child has a unique pattern of hearing loss which is typically different in each ear.
Audiologists measure hearing loss and show the results on audiograms (charts similar to the picture on the right). It is important to have regular hearing tests so that children can be given effective hearing technology.
Causes of hearing loss
There are many causes of hearing loss. It is not always possible to identify the cause. Audiologists and/or paediatricians may be able to investigate/identify the cause. Possible causes of hearing loss include: a genetic condition, a viral infection during pregnancy, a head injury.
