UHL - Hearing & Hearing Loss
Hearing – how do we hear?
The ear consists of 3 main parts:
The outer ear
The middle ear
The inner ear
The outer ear consists of the pinna (the external part of the ear) and the ear canal. The pinna gathers sound and funnels it into the ear canal towards the eardrum.
The middle ear includes the tympanic membrane (eardrum) and the ossicles (the 3 smallest bones in the body). When soundwaves reach the eardrum, the energy is mechanically transferred through the ossicles to the inner ear.
The middle ear is a small air filled space. The middle ear air pressure is equalized by the eustachian tube, which connects the middle ear with the back of the nose and throat.
The inner ear contains the hearing organ and the balance organ. The hearing organ (the cochlea) is responsible for converting the vibrations received from the middle ear into nerve signals which are sent along the auditory nerve to the brain.
The balance organ (vestibular system) contains the semi-circular canals and the otolith organs and is responsible for helping us maintain balance.
Hearing Loss
A hearing loss can occur if there is a problem at any part of the outer, middle or inner ear. The type of hearing loss is characterised by which part of the auditory system is affected. There are 3 types of hearing loss:
Conductive
Sensorineural
Mixed
A conductive hearing loss is caused by a blockage in the outer and or middle ear. This can be temporary or permanent. Some conductive losses can be treated with medical intervention or surgery.
A sensorineural hearing loss is caused by damage to the inner ear (the cochlea) or the hearing nerve. This type of hearing loss is permanent.
A mixed hearing loss is a combination of conductive and sensorineural components.
The impact on your child’s everyday activities and their speech and language development will vary depending on the degree of hearing loss. A unilateral hearing loss can vary in degree of severity - from mild to profound. Your audiologist will be able to discuss the degree of your child’s hearing loss and the type of intervention and management that may be necessary.
General difficulties may include:
Knowing the direction/location a sound is coming from
Understanding speech in noisy environments
Hearing someone speaking on the affected side
Poor sound quality
Speech and language development
Social interactions
What is Unilateral Hearing Loss?
A UHL is a type of hearing impairment where there is normal hearing in one ear and impaired hearing in the other ear. The hearing loss can vary in degree from mild to profound. Degree of hearing loss is generally described using the following categories:
Mild hearing loss (a child with a mild hearing loss can hear some to most speech sounds but have trouble hearing soft sounds, e.g. rustling leaves)
Moderate hearing loss (a child with a moderate hearing loss will have difficulty hearing speech at a conversational level)
Severe hearing loss (a child with a severe hearing loss will not hear any speech at a conversational level but may hear some loud voices)
Profound hearing loss (a child with a profound hearing loss will only hear some very loud sounds, e.g. motorcycle)
What are the causes of hearing loss?
Hearing loss can be congenital, acquired or idiopathic.
A congenital hearing loss means that the hearing loss is present at or very soon after the time of birth. A congenital hearing loss may be caused by hereditary factors, difficulties or health problems during pregnancy, or genetic disorders.
An acquired hearing loss means the hearing loss occurs after birth. This could be the result of an illness such as meningitis or mumps, ototoxic medications, recurrent ear infections or physical trauma such as a head injury.
An idiopathic hearing loss means that there is no known cause for their hearing loss. This occurs in approximately 25% of children.