There are several types of technology that assist some deaf people to hear more than they do without the technology. There are two main types of technology that are worn. They are:
- hearing aids – these are worn on the outside of the ear
- cochlear implants – these have a component that is surgically implanted as well as a component that sits on the outside of the ear
Whilst these two things can look similar, they actually work in very different ways.
As noted, these are entirely external to the body and their sole purpose is to amplify sound to assist the deaf person in his or her perception of sound. For some but not all, hearing aids also assist in the perception of speech.
The word “perception” is very important because, unlike glasses, hearing aids do not and cannot correct how sound is heard. They only amplify sound and speech.
So, if the deaf person has a damaged auditory nerve – which is often the case – whilst a hearing aid will assist him or her to perceive sound by making it louder, it will still be heard as distorted, incomplete or both.
Obviously, this is very different to most people’s experience of glasses whereby vision is unclear, blurry and/or indistinct but by putting on glasses, everything is seen sharply and clearly. This is because glasses are correcting how the eye sees.
In addition, hearing aids also tend to amplify all sounds equally, so background noise can be difficult as often these noises are heard just as loud as sounds that the user is trying to hear. There are some technologies that can assist a hearing aid user to cut out background noise; these require the speaker to wear a special microphone.
Cochlear implants or CIs
The first step with a CI is for the deaf person to undergo a delicate operation to insert 22 electrodes into the cochlea or inner ear. This is where the auditory nerve is in the body. At the same time, a magnet and a receiver/stimulator are also placed against the skull bone, just under the skin.
Once healing is complete, an external part of the CI which has a sound processor is worn on the ear and a transmitter runs from this and is attached to the receiver using the magnet.
This device works very differently to hearing aids as it transmits sound directly to the 22 electrodes that sit on the auditory nerve. Then, as is the case with people who have hearing, this sound stimulation is carried to the brain via neural pathways in order for the brain to interpret the sound and the individual to hear it.
It is important to understand that whilst a CI does provide sound stimulation directly to the brain, it does not provide normal hearing. Often, media portrayal of the CI is inaccurate, so it is common for many people to think that a CI makes a deaf person hearing. This is not the case. It provides sound stimulation that the user needs to learn to understand. There are varying degrees of success for users of CI; results are very individual and a number of factors come into play.
Originally, people were allowed to only have one ear implanted; however, in recent times, it has become more common for people to have both ears implanted with cochlear implants. However, these are still done one at a time.
To hear a simulation of sound through a cochlear implant, click here