Hearing in background noise
The reason we, with implants, struggle in background noise is because of microphones. Unlike our natural ears, microphones are unable to discriminate between good noise and bad noise. A basic microphone will pick up any noise around and amplify it. While Cochlear Implant (and hearing aid) microphones are a little more sophisticated they still don’t have the discrimination to cancel out what we don’t want to hear.
So how can we set our Cochlear Implants so we can manually help our processors cancel out the noise we don’t want to hear?
First of all bear in mind that a Cochlear Implant doesn’t amplify sound. Our processor picks up the vibrations of sound and translates these into an electrical impulse. These electrical impulses travel down the cords to the electrodes inserted in our Cochlear where the impulses stimulate our hearing nerve in the same way as those cochlea hairs do for a hearing person.
Now let’s examine what the two major settings do – Sensitivity and Volume.
Sensitivity, the setting with the symbol which looks like a target, determines how far away we hear sound. Imagine you are standing in the centre of the target and there is a glass circle around you. If the circle is small then you hear only the small amount of sound which is inside the circle and the less you hear of anything beyond that glass circle. If you pushed the glass circle further away from you then you would hear more things within the circle. This is what sensitivity does it reduces the circle or distance where you will hear sounds.
Volume on the other hand increases or reduces the sound you hear – as does any volume control on anything else. However, it reduces or increases the volume with reference to the Sensitivity or the circle you are in.
How this interprets for us
Reduce the Sensitivity (or make the circle you are in smaller) but increase the volume means you will hear louder within the range of that circle. Increase the Sensitivity but reduce the volume means you will hear further away but at a lower volume.
Let’s assume that a Sensitivity of 12 equals a distance of 20 feet (it doesn’t but just as an example). This means your glass circle is 20 feet away. You will hear everything within this circle at the Volume you have set. If you’ve reduced your volume to (say) 5 – everything will be very soft, even those things close to you. If there is background noise that’s pretty much all you’ll hear.
On the other hand if you reduce your Sensitivity to 6 (say it is 10 feet) and leave your volume at 10 then you will hear everything quite loudly within a range of the 10 feet.
How this applies for you in real life is often trial and error. Reducing the volume won’t help you hear in background noise. It will simply reduce the volume for everything you hear. On the other hand reducing the sensitivity but keeping your volume higher will block out a lot of the background noise which is further away from while still allowing you to hear those close to you. When I am travelling on an aeroplane I reduce my sensitivity to 2 but keep my volume at 10. This means the jet engine noise, which is further away from me is reduced to the sound of a kettle boiling in the background, but I can still hear the people sitting next to me and the cabin crew as well as the captain’s announcements.
This process seems counter intuitive but it is actually what the auto sensitivity programs do (to some extent). Reducing the sensitivity but increasing the volume actually gives a better outcome for hearing in noisy environments.
You Should Also Read:
Frustrations of deafness
Recognising noise in our environment
Tips for music with a Cochlear Implant
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