The Advantages of Binaural Hearing: Why Two Hearing Aids May Be Better Than One
If you’re a new hearing aid user or considering using hearing aids, you might wonder if you need one or two devices. The answer often lies in the concept of binaural hearing - the ability to hear with both ears. Binaural hearing allows us to hear sounds in three dimensions.
Just as your brain uses the images that each of your eyes see to create one cohesive picture, your two ears working together creates this spatial perception. The two halves of your brain work together to give you an auditory image.
Our brain uses the subtle differences in the sounds each ear hears to help us locate the origin of a sound. Hearing does not happen in your ears but in your brain. If you’re using one hearing aid when your hearing test indicates that you should be using two, the chances of your brain getting all the information it needs to hear and understand reduces by 50%.
Here's a detailed look at the benefits of binaural hearing and why two hearing aids are often recommended.
Understanding Binaural Hearing
When you use both ears for hearing, the term is binaural hearing, you give your brain additional auditory information to process. Your right ear transmits sounds to your left brain region before your left ear sends signals to your right brain region. Your brain processes sounds from both sides before the entire brain creates a unified interpretation of the heard information.
Similar to stereoscopy, stereophony is based on combining information in the brain from the two ears, creating a robust illusion that confers the stimulus a special character of perspective known as three-dimensional (3D) depth and localisation. Both in the visual and auditory modalities, this character contributes to creating ‘objects', which are easier to segregate and identify than what would have happened if a single receiver had been available.
Key Advantages of Binaural Hearing Aids
There are several compelling reasons to consider binaural hearing aids, especially if you have hearing loss in both ears.
1. Improved Speech Understanding in Noisy Environments
One of the most important benefits of binaural hearing aids is improved speech understanding, especially in noisy environments. Voice discrimination when you’re competing with background noise is difficult even with two ears and becomes almost impossible with only one. The majority of individuals with hearing loss face difficulties hearing in noisy environments. Binaural hearing enables individuals to hear more clearly by helping to pull what you want to hear out of background noise more successfully.
In noisy environments with multiple people speaking at once, like at a restaurant, it becomes more difficult to understand the one person at the table with you.
An essential task for the central auditory pathways is to parse the auditory messages sent by the two cochleae into auditory objects, the segregation and localisation of which constitute an important means of separating target signals from noise and competing sources. Thus, when submitted to this analysis, competing activities will be identified as separate objects located in different directions to which it will be much easier to pay (or not pay) attention than it would have been with a monaural input providing a flat, 2D sound landscape.
2. Enhanced Sound Quality and Natural Hearing Experience
Just as stereo sound is more enjoyable than mono, hearing with two aids usually provides a richer, more natural sound experience. Anyone who has listened to music in stereo, as opposed to mono, knows that it’s necessary for depth perception. Mono makes all sounds seem flat and unnatural. Your hearing is the same: your brain can hear in stereo, but it requires that we use both ears.
When hearing aids are correctly fitted to both ears, your brain achieves better sound processing accuracy.
3. Reduced Listening Fatigue
Listening with one ear can be more tiring than listening with two. With two hearing aids, the listening effort is shared between both ears, reducing fatigue.
4. Prevention of Auditory Deprivation
Using a hearing aid in only one ear could potentially lead to auditory deprivation in the non-aided ear. Over time, the unaided ear might lose its ability to understand speech.
In the case of asymmetric hearing loss, some aspects are so degraded in the poorer ear relative to the better one that comparison between the two ears may become impossible.
5. Better Sound Localization
Binaural hearing allows you to detect what direction a sound is coming from. For example, sound coming from a source on the right side of a subject reaches the left ear later than the right ear, as it has to travel further, and it reaches it with a lower intensity, as it has experienced the head shadow effect. The further to the right the source is located, the larger the interaural differences.
The evolutionary advantage of this ability to detect a predator stealthily approaching its prey while the latter drinks near a noisy waterfall is so huge that the brain has developed and maintained impressively refined stereophonic systems.
6. Improved Selective Listening
The brain's cooperative function enables selective listening. Your brain uses this method to block out unnecessary noises when you need to listen to a distant voice during meals, at restaurants, or when speaking with family members.
7. Less Amplification Needed
Also, a person wearing two hearing aids generally needs less amplification than someone wearing only one. Using two hearing aids requires adjusting the volume down for each device.
The Science Behind Binaural Hearing
Audition, including its stereophonic abilities, is a complex process in which peripheral analysis in the cochlea is only a first stage. One important function in the brain, to combine and compare the raw information from the two cochleae, occurs in different brainstem nuclei, notably in the olivary complex, which exploit the intensity, timing and frequency aspects of what the cochleae have encoded. From their (hopefully consistent) outputs, a 3D landscape is built.
A first, basic consequence is the fact that each of the two ears substantially contributes to the action potentials that reach the brainstem, referred to as binaural loudness summation (a particular case of the more general notion of binaural redundancy). Very roughly speaking, the feeling of loudness generated by a sound relates to the number of action potentials triggered by the sound and integrated in (as yet unknown) brain centres.
Not only do signals sound louder when subjects listen with both ears than with one ear, but the treatment of information is more sensitive to small differences, which when occurring unilaterally would be more difficult to separate from chance events. Thus, the just noticeable differences in intensity and frequency improve with signal redundancy and, thus, bilateral presentation. Likewise, recognition is improved in the presence of noise.
Other Considerations
Hearing loss often occurs in both ears, a condition known as bilateral hearing loss. In these cases, wearing two hearing aids can be beneficial as it aligns with the natural binaural hearing process. We sometimes see patients with hearing loss in only one ear (also known as unilateral hearing loss), but typically the factors that led to hearing loss affected both ears - just to a different degree.
The condition where hearing deteriorates differently in one ear compared to the other affects numerous individuals. Patients often inquire as to whether they can limit their hearing aid treatment to their more severely damaged ear. Patients with unilateral hearing loss come for evaluation of their hearing difficulties in one ear. The majority of cases involve hearing loss that affects both ears, although one ear shows greater deterioration.
While there are clear benefits to wearing two hearing aids, the decision is best made in consultation with your audiologist. Adjusting to binaural hearing aids might take some time. Be patient with the process and communicate with your audiologist about any concerns or difficulties you may have.
Alternative Solutions for Unilateral Hearing Loss
In less common cases in which there is a total hearing loss in one ear (also known as profound unilateral hearing loss or single-sided deafness), there are medical therapies that may help to re-create some of the effects of binaural hearing. These include bone-conduction systems (also known as bone-anchored hearing aids, or BAHA devices) that can help transmit vibrations from the nonhearing ear to the functioning ear.
The BAHA (Bone-Anchored Hearing Aid) serves as a bone-conduction device that patients can use. A CROS system (Contralateral Routing of Signal) functions by using a microphone on the deaf side to transmit sound wirelessly to a hearing aid placed in the better ear.
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Seeking Professional Advice
Following your hearing specialist’s advice is a crucially important step in your hearing journey. While it may be tempting to try and do with only one hearing aid, we think the benefits of binaural hearing are too crucial to ignore. Wearing two hearing aids can bring us closer to the natural hearing experience and provide many advantages, especially for those with bilateral hearing loss.
But, remember, each person’s hearing loss journey is unique. Your audiologist is there to guide you through this process, ensuring that you get the most out of your hearing aids and improving your communication and participation in life’s beautiful symphony of sounds.
Every person has different hearing loss needs, which require individualized solutions. We encourage you to schedule a hearing evaluation to determine your hearing needs.
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