hearing aids

how do hearing aids generally work?

amplifying sound to assist individuals with impaired hearing

what are the indications of hearing aids?

CHL and SNHL

what are the two different types of hearing aids in terms of mechanism?

analogue and digital

how do analogue hearing aids work?

convert sound waves into electrical signals, which are amplified

how do digital hearing aids work?

- convert sound waves into numerical codes before amplifying them

- code also includes info about a sound's pitch or volume, so it can be specifically programmed to amplify some frequencies more than others

what are the different types of placement of hearing aids?

- completely in the canal (CIC)

- in the canal (ITC)

- in the ear (ITE)

- behind the ear (BTE)

what does a CIC hearing aid look like?

what does an ITC hearing aid look like?

what does a behind the ear hearing aid look like?

what is a BAHA?

bone-anchored hearing aid

how do bone-anchored hearing aids work?

sound is transmitted to cochlea via bone conduction

what would be the indications of bone-anchored hearing aids?

intolerance of conventional hearing aids:

- persistent draining ear

- congenital malformations

- unilateral deafness

what are the complications of bone-anchored hearing aids?

skin regrowth around titanium screw and non-osseointegration

what is non-osseointegration?

when an implant becomes so fused with a bone that it is impossible to separate them without fracture

what are cochlear implants?

surgically implanted electronic devices that electrically stimulate CNVIII

what is a prerequisite for cochlear implants?

auditory nerve and system are intact

what are the indications for cochlear implants?

children - audiological assessment and/or difficulty developing basic auditory skills

adults - unsuccessful prior attempt with hearing aids for 3 months

what do cochlear implants look like?

what are the contraindications to cochlear implants?

- lesions of CNVIIII or the brainstem

- chronic infective otitis media

- mastoid cavity or tympanic membrane perforation

- cochlear aplasia

what are the complications of cochlear implant surgery?

- facial nerve injury

- CSF leakage

- meningitis

what should be ensured to reduce the risk of meningitis?

up-to-date vaccinations against streptococcus and haemophilus