It was interesting for me to hear from a number of patients that if you have hearing loss on both sides, it's better to use only one hearing aid! The misconception among this group of patients is that when you use hearing aids, you are actually helping your natural hearing system and by doing that you make your hearing becomes lazy, hence your hearing might even decline faster!
Just recently in a hearing test in a patient's home in Crystal Palace, right after the hearing test, the patient asked me "So, do you think I need hearing aids?", "Absolutely", I replied. "Oh, really, so do you think I need one or two hearing aids!??!"
If you have hearing loss in both ears, you should be wearing two hearing aids, period. It is very similar in concept to your vision. If you have issues with your vision on both sides, you would require different lenses for each side, but you use a pair of glasses that hold two different lenses for your eyes.
Here are some audiological explanations as to why you need two hearing aids if both of your ears have elevated hearing thresholds:
Noise reduction: When you are in a noisy environment your brain can still understand the speed. The reason is that most of the time in a noisy environment the speech signal and the noise signal that arrive at each ear are different from the one that arrives at the other ear. The human brain has its own noise reduction capability. By analysing the arrived signals your brain picks the one which is clearer and less distorted by the background noise. Having two hearing aids means that you allow your brain to do its noise reduction job optimally, and more naturally.
Localisation: Your brain analyses the information from both ears and compares and contrasts them. By analysing the time delays as well as the difference in the loudness of the sound received from each ear, the brain is able to determine the location of the sound (the direction that the sound is coming to us), and the distance of it. In the other words, if you have a better hearing on one side than the other, you can't accurately tell what direction sounds are coming from.
Binaural summation: The sound from each ear is analysed at different steps when on its way up to our auditory cortex. When the two signals arrived in the brain, they will be compared and summed up together to make a better level (louder) and meaning of it. Very often, the hearing loss of each ear is different from the other one hence having two hearing aids would reduce the need for a higher gain in both aids, compared to the gain in one hearing aid when only one is fitted.
Head shadow effect: High frequencies of the speech spectrum is the part of the sound that gives clarity to speech. While low frequencies can be heard better by both ears even when you hear them from one side, the high frequencies of the speech presented on one side will be highly attenuated when it arrives at your other ear. This is called the head-shoulder effect. Hence the clarity of the speech on your unaided side will be poor if someone is talking on your aided side.
Sound quality: Human brain is designed to hear in stereo. Hearing from one side sounds a lot less natural to us.
