Hearing Aids vs. Hearing Implants: When Hearing Aids Are No Longer Enough
With the introduction of digital technology and advanced signal processing, most cases of hearing loss can be rehabilitated with the use of hearing aids.
Nevertheless, to benefit from the use of hearing aids, a user’s ears must still retain some residual hearing to process the amplified sound, as well as a minimum dynamic range of 30 to 40 dB to process speech information.
As a result, patients with profound hearing impairment, single-sided deafness and chronic ear infections may find hearing aids inadequate. These patients will likely see more benefits from hearing implants.
For: Profound Hearing Loss
For individuals with profound hearing loss, hearing aids are of limited benefit as the cochlea is unable to process sounds, however much amplified. With cochlear implants, these patients can once again regain the ability not only to understand environmental sounds but also enjoy social conversations.
The cochlear implant system consists of an external speech processor that sits behind the ear, and an implant portion that is surgically placed under the skin.
How a cochlear implants works
- The microphone in the external speech processor picks up sounds from the environment
- The speech processor analyses the sound and converts it to digital signal
- The digital signals are sent to the coil and transmitted across the skin to the implant
- The internal implant sends the signal to electrodes, which stimulate the hearing nerve directly, bypassing the damaged cochlea
- The brain recognises these signals as sound
It must be noted though, that as hearing through a cochlear implant is different from normal hearing, a substantial amount of time is required for before a user is able to adjust to hearing with the implant.
Bone Anchored Hearing Aid
For: Conductive/Mixed or Single-Sided Hearing Loss
Sound can reach the inner ear through two paths:
- By air conduction via the ear canal and middle ear to the inner ear.
- By bone conduction where vibration bypasses the outer and middle ear and is conducted directly to the inner ear.
The bone anchored hearing aid (BAHA) system uses a process called direct bone conduction. A small titanium implant is placed in the bone behind the ear where it osseointegrates with living bone.
This osseointegration takes about three months for adults and six months for children. Once the osseointegration is complete, an abutment is attached to the fixture and a sound processor clipped on. Sound will be picked up by the external processor and conducted directly through the bone to the inner ear.
For patients with single-sided profound hearing loss, the BAHA system is placed on the deaf side where the device will pick up sound and conduct it to the working cochlea of the good ear. This allows patients with single-sided hearing loss to hear sound from both sides.
Since the BAHA system does not have any component in the ear canal, patients with recurring ear infections can leave the ear canal open and dry, thus reducing further incidence of ear infections.