One or two hearing aids?

February 15, 2010
Why wear two hearing aids?
People with bilateral hearing loss often question the need for two hearing aids. “I know someone who wears just one hearing aid. Why must I wear two?”

“Can I start out by wearing only one hearing aid and wait to see if I need one for the other ear?” There are good reasons why humans are born with binaural or “stereo” hearing. To begin with, two ears are essential for determining where a given sound is coming from—an ability known as sound localization. Binaural hearing also makes it easier to understand speech, particularly in noisy places. It can be tempting to want to amplify sound in just one ear. Unfortunately, this often yields a less-than-optimal outcome, even if the single hearing aid used is highly sophisticated.

“Bilateral hearing loss” is the term used to describe hearing loss that affects both ears, while loss of hearing in only one ear is known as “unilateral hearing loss.” Some studies would indicate that 80% of hearing-impaired people are affected in both ears (bilaterally). Presbycusis—the gradual loss of hearing related to age—is the most prevalent form of bilateral hearing loss, since it’s caused by the natural aging process. Hearing loss can also be congenital (present at birth) or noise-induced (work-related).

Do I really need two hearing aids to be able to hear properly?


Sound localization refers to the human auditory system’s ability to pinpoint the location or origin of a detected sound through a range of physical cues. One such cue is known as the interaural time difference or ITD. Sounds reach each ear at slightly different times and amplitudes: tiny differences that tell us whether the sound is coming from the right, left, front or rear. This information is vital in many situations. For example, in traffic, it’s what lets the driver determine which direction the blast of a horn from another vehicle is coming from.


When the brain receives sound through both ears rather than just one, it has a greater selection of acoustic information to process. Decoding words thus becomes easier, particularly in loud settings. For this reason, binaural hearing aids can improve speech comprehension in noisy environments.


Binaural amplification (amplifying the sound in each ear) allows both ears to receive sound at the same time, meaning that you pick up sounds and speech coming from both your left and your right. Such relatively equal hearing leads to a more balanced sound quality, which in turn makes it easier to understand speech.


Having two hearing aids instead of one increases the range of sound perception from 180° to 360°. Stereophonic sound is richer in tone and feels more natural. It’s life in stereo! People with normal hearing rarely think about the mechanisms of hearing—as is only to be expected. However, for anyone who experiences hearing loss, understanding how it can affect quality of life becomes very important.

Next time you visit your audioprosthetist at one of Lobe Santé auditive et communication clinics, take the time to discover all the undeniable advantages of wearing two hearing aids.