News & Information

Jun 11 2013

Sound localization – why two ears are better than one

Imagine walking down the street and hearing a siren, but not being able to tell where it is coming from. This can be a very frustrating or scary experience for people with hearing loss.

Sound localization depends on both ears working properly. If a sound comes from the right side it reaches the right ear slightly before it reaches the left. It will also be little bit louder in the right ear. This time and level difference is called the “head shadow effect” and it tells us if the sound is coming from the left or the right. The shape of the outer ear (pinna) is designed to filter sound into the ear when it is coming from the front. This “pinna effect” tell us if the sound is behind or in front of us. The combination of the head shadow and pinna effects tell us where sound is coming from.

When one has a hearing loss these effects are compromised, especially if there is even a small difference in hearing between the ears. For example, a person wearing one hearing aid will hear sounds much louder in that ear. Everything will sound like it is originating from the side that the hearing aid is on, even if it is coming from the opposite side of the head. The hearing needs to be the same in both ears in order to localize sound.

Because the hearing needs to be the same in both ears, wearing two hearing aids can help those with hearing loss localize sound. Most of today’s hearing aids also have directional microphones. The microphones are oriented so that there is one in the front and one in the back. This helps to recreate the pinna effect. Some hearing aids also use “binaural communication.” This means the hearing aids share information in real time. This allows them to process very slight timing differences between the ears, which in turn improves sound localization.

Two hearing aids with the above features can help restore some sound localization. While wearing two hearing aids will improve your hearing and localization, they will not restore it to normal. There are many types of hearing loss and factors that determine how well hearing aids will work. A complete evaluation of your hearing and specific listening needs is required to determine the right hearing aids for you. With the proper instruments your hearing and quality of life can be greatly improved.

If you have concerns about your hearing please give our office a call at 252-3004 in Lower Sackville or 423-7734 in Halifax.

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