In real life, some hearing-impaired patients choose to be fitted with a hearing aid in only one ear. This may be due to financial reasons or they may be skeptical about the effect of bilateral fitting. So why do humans have two ears? Is it just for good looks? Obviously not.
Bilateral fitting is very important in our daily lives. Except for hearing-impaired patients with contraindications, they should all choose bilateral fitting of hearing aids.
The benefits of bilateral fitting include the following points:
Improve the ability to localize the sound source
Both ears can determine the direction of the sound source based on the time and loudness of the sound arrival. When wearing a hearing aid in only one ear, there is no ability to locate the sound in the left and right directions. When listening to sound with one ear, the sound always comes from one side, and the sound on the other side always feels very far away. In this way, when a hearing-impaired person is on the road, the ability to localize the sound source with both ears cannot be exerted, which adds many unsafe factors to oneself.
Improve speech discrimination in noisy environments
Regardless of whether the hearing loss of both ears of a hearing-impaired person is symmetrical, using two hearing aids simultaneously in both quiet and noisy environments can significantly improve speech resolution compared with using only one hearing aid in one ear, and the effect is also significantly better than wearing only one hearing aid.
Eliminate the head shadow effect
Sound is composed of high-frequency, medium-frequency, and low-frequency sounds. When the sound reaches both ears, it will be blocked by the head. And the high-frequency components in speech are not easy to diffract around the head due to their short wavelengths. When the sound source is on the side without a hearing aid, due to the blockage of the head, some high-frequency sounds will be missing, and the effect on the side with the hearing aid will be affected.
Cumulative effect
For severely or extremely severely hearing-impaired patients, bilateral fitting of high-power hearing aids can utilize this supra-threshold cumulative effect to achieve an effective comfortable loudness level.
Effect on auditory deprivation/degeneration
Human hearing has the characteristic of “use it or lose it”, and it needs long-term stimulation to maintain sensitivity. After wearing a hearing aid in only one ear, the ear with the hearing aid will be used to listen to sounds for a long time, and the ear without the hearing aid cannot receive effective stimulation, and its speech recognition rate will gradually decline and degenerate. Years later, when you want to fit a hearing aid for this ear, the effect will not be very good either.
Studies have shown that after using hearing aids in both ears for 4 – 5 years, the speech discrimination rate of both ears remains stable; while if only one ear is used, the speech discrimination rate of the contralateral ear without a hearing aid will decline after 4 – 5 years.
Improve sound quality
Although the improvement in speech discrimination rate of some hearing-impaired people using bilateral hearing aids is not obvious, most users will feel that the sound quality has improved. For the first time using a hearing aid, it is much easier to satisfy the hearing-impaired person by debugging bilateral hearing aids than using a single hearing aid.
Easier listening
People wearing bilateral hearing aids are more relaxed when communicating with others, and it is easier for them to listen to people talking than those using only one hearing aid.
Noise reduction effect
When wearing hearing aids in both ears, the background noise is not easy to mask the speech sound, and it is easier for hearing-impaired patients to hear the speech sound clearly.
Alleviate or suppress tinnitus
The most common method for treating tinnitus now is the tinnitus masking method, and most scholars agree that the best tinnitus masker is a hearing aid. This method is the sound masking tinnitus treatment method, especially when using both ears.
Reduce reverberation
People with hearing loss are more easily interfered by the reverberation of the surrounding noise than those with normal hearing. Bilateral fitting has an advantage over unilateral fitting in reducing reverberation.
Integration effect
Auditory function has a cerebral hemisphere advantage. Basic speech and language processing occurs in the left cerebral cortex, while the recognition of pitch and intonation occurs in the right cerebral cortex. It is necessary for both the left and right ears to participate simultaneously to facilitate understanding and memory.
The attitudes of hearing-impaired patients and audiologists
The vast majority of audiologists highly recommend bilateral fitting, and hearing-impaired people also tend to use two hearing aids after a trial fitting. The role of this in improving speech discrimination and sound source localization is beyond doubt.