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Unilateral versus Bilateral Amplification

A majority of the population with hearing loss have the presence of hearing loss in both ears. Hearing loss is most commonly symmetrical. Therefore, a majority of patients treat both ears with the purchase of bilateral amplification. Typically, patients have better performance with two hearing aids versus one hearing aid. Although contraindications such as cost, maintenance, and degree of hearing loss (too bad or too good in one ear) may prompt patients to purchase only one hearing aid, there are several advantages for utilizing two hearing aids if a patient is a candidate for amplification in both ears.


When two hearing aids are used, it takes less sound intensity to maintain equal loudness in both ears. Regularly there is a head shadow effect which attenuates sound by 10-15 dB when sound arrives from the opposite side. This means that the ears will not receive sound at the same intensity. Using two hearing aids can help eliminate the head shadow effect.


Sound localization is improved when two hearing aids are worn if hearing loss is symmetrical. This helps patients locate which direction a sound is coming from.


An additional advantage of using two hearing aids is improved speech perception in noise by approximately 1-2 dB. Although this seems like a small difference, each 1 dB improvement in the signal to noise ratio may provide an increase of approximately 10% in word recognition score. That is, speech being the signal, and noise the secondary sounds in one’s environment. The goal is to make it easier for a patient to identify, locate, separate, and interpret speech. This is beneficial for understanding speech, especially in background noise.


If hearing loss is present in both ears, and only one ear receives a hearing aid, there can be some disadvantages. A huge disadvantage is that having only one hearing aid can lead to a reduction in word understanding of the ear without a hearing aid over time. The ability to localize to sound can be diminished if only one ear is receiving amplification. Using only one hearing aid can also reduce perceived sound quality. Some patients may be overwhelmed with maintaining two hearing aids versus one when physical constraints apply such as vision loss and poor dexterity. In this scenario, a patient should work with a provider to accommodate the patient’s specific needs.


A recommendation from a hearing care provider can help to provide patients with an informed decision regarding treatment of hearing loss by utilizing amplification. A hearing aid consultation can be scheduled with an audiologist to provide patients with options and an opportunity to trial amplification may be available to a patient before fully committing with hearing devices.


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