The Binaural Advantage -- why are two hearing aids better than one?

by Hazel Inglis, August 10, 2000
HearingCenterOnline.com Staff writer

Hearing aids cost a bundle, there is no doubt about that. Manufacturers spend oodles of money researching and developing them and audiologists devote a lot of time testing, fitting, and making adjustments for each patient (not to mention the amount of time they invested to get their degree). As hearing aids are sold in relatively low quantities (1.7 million hearing aids for some 30 million hearing impaired in the US*) these costs must be recuperated -- and unfortunately like most things in this less than perfect world, that cost is transferred to the consumer.

So ... considering the hefty cost of just a single hearing aid (which usually ranges from $700 - $3000) why on earth would you invest in two? Well, to start with, I'm sure you've heard the expression, ‘two heads are better than one'. Studies show that ‘two hearing aids are also better than one.' In fact, there are many benefits to binaural amplification (two hearing aids), including: better hearing in noise, enhanced sound quality, increased ability to detect the source of a sound (localization), and prevention of a condition called ‘adult onset auditory deprivation'.

To understand these benefits, it is first important to realize that we hear in our brains, not in our ears. Your brain processes the information received from both ears to ‘paint' an ‘auditory picture' of your surroundings. If your brain receives a signal from just one ear not only will it have to work twice as hard, (which is more tiring and stressful for you) but it will have less information with which to paint this ‘picture'. Don't follow? Try this. Cover one eye and look around ... now uncover it. Do you see how much more area you are aware of without that eye covered? A grossly simplified explanation, but you get the drift.

The first benefit of using two hearing aids is improved hearing in a noisy environment. First of all, for the monaural user (one hearing aid) who is in a situation where everyone is talking at once, it becomes harder to pick out individual voices. Remember, even those with ‘normal' hearing in both ears have difficulty understanding the people they're with in places such as a restaurant or bar. This could be potentially embarrassing in a social or business setting, if you do not acknowledge a person speaking to you on your unaided side.

Another factor to consider is that wearing two hearing aids improves sound quality. Binaural hearing requires less volume, which makes listening more comfortable and less tiring. Secondly, with messages being sent to both ears, the brain is capable of hearing things in ‘stereo'. This gives the listener a natural, balanced ‘3-D' sound which can be understood more clearly.

A third advantage to binaural listening, is an enhanced ability to ‘localize' a sound source. According to the American Academy of Audiology, "We determine where a sound is coming from on the basis of 1) the relative time in which the sound arrives at each ear, 2) the relative difference in loudness at the two ears, and 3) the relative difference in the pitch of the sound at the two ears. When there is a large difference in hearing between two ears ... the brain cannot make use of these subtle differences and [one's] ability to locate sounds may suffer..."* In other words, if hearing is not balanced between two ears, it becomes very difficult to determine the source of the sound. Not only will knowing the sound source avoid confusion in traffic and crowds, but it can alert you to a potentially dangerous situation, such as the approach of a vehicle ... or a piano falling from the sky (hey, it could happen ... although someone would probably have to be playing it for you to hear it).

Finally, research suggests that monaural users may suffer from a phenomenon called ‘adult onset auditory deprivation'. That is, if the ear is not stimulated, its ability to understand speech may deteriorate over time. To paraphrase part of SHHH's (Self Help For Hard Of Hearing People) position statement on hearing aids, "this deterioration is thought to be reversible if a hearing aid is latter fitted (providing the ear is suitable for amplification). However, if one is deprived of stimulus for too long (undefined ) ... then this deterioration may be inevitable. That is, if we don't ‘use' it, we may indeed ‘lose' it."**

So what next? Ultimately the choice to seek binaural amplification is a decision best made between you and your hearing specialist. However, it is important to be informed about all the repercussions of your decision. If you have any questions and concerns please don't hesitate to discuss them with your audiologist.

References:

* American Academy of Audiology

Refer to: http://www.audiology.org/consumer/hafaq

** Self Help For Hard of Hearing People, Inc. position statement on hearing aids.

Refer to: http://www.shhh.org/position/hearaid.htm

Kochkin, Sergei and Francis Kuk. "The Binaural Advantage: Evidence From Subjective Benefit & Customer Satisfaction Data" The Hearing Review, Vol. 4, No. 4, April 1997, pp. 29-32, 34.