There are a number of reasons that a child or adult may have persistently reduced hearing on one side, but not on the other. This is sometimes called ‘single sided deafness’ (SSD). This may be something you are born with, or something that happens to you over the course of your life. There is an increasing recognition of the difficulties that this can cause.
We know that hearing loss on one side means that it is more difficult to work out what someone is saying in a noisy environment. Particularly when someone is talking to you from the side you can’t hear, and there is some noise like another conversation happening in the direction of your good ear. Listening in the real world is very different from the way in which hearing is commonly tested - throughout the day we are surrounded by many sources of noise, some of them relevant, and some of them not relevant. We also know that single sided hearing loss means it is much more difficult to work out which direction a sound is coming from, and you have to put a lot more effort into working out what is being said (1). In children, single sided deafness can cause delays to speech, and may affect educational attainment (2).
We group hearing loss into two categories - ‘sensorineural’ hearing loss - where the hearing organ (cochlea) itself is not working normally, and ‘conductive’ loss where the hearing organ itself is working normally, but sound can not get to it. Both types of hearing loss can be seen in children and adults. For more information see here. Sensorineural hearing loss has a number of causes, but is most commonly caused by age. Conductive hearing losses may be due to long-standing infections in the affected ear, head injuries, or conditions you are born with such as ‘little ears’ (microtia and atresia).
There are a variety of options to treat this condition. If the hearing loss is ‘conductive’ then procedures or operations to repair the hearing mechanism are usually possible. The exception to this is ‘microtia/atresia’ (being born with little ears), in which operations to restore ‘natural’ hearing are not usually advisable, and we generally recommend a bone conduction hearing aid in the first instance, and then an auditory implant of some sort. If the cause is a sensorineural loss, then the options are as follows:
a normal hearing aid. This is used when there is still some hearing in the affected ear.
a CROS aid. This is a type of hearing aid that is worn on both ears. There is a microphone that is worn on the side of the hearing loss, and a speaker on the side where the hearing is better. They are connected using Bluetooth. That way if someone talks to you from the direction you can’t normally hear, the sound is communicated to the ear with which you can hear. Information about CROS aids is accessible here.
A Bone Conduction Device (3). A bone conduction device is a type of hearing aid that vibrates the skull rather than playing sound. Vibrations of the skull stimulate the hearing organ directly. Because there is solid bone between one side of the head and the other, wearing this kind of a device on the skull on the side you can not hear can stimulate the hearing organ on the other side of your head. This lets you hear when sounds are directed to the ear with the hearing loss. Methods to comfortably secure the vibrating hearing aid to the skull can require an operation. Names of bone conduction devices include BAHA, Ponto, and Bonebridge. Information about bone conduction devices in single sided deafness is available here.
A Cochlear Implant is the only way by which the sensation of hearing can be given to an ear that has completely lost hearing (4). This involves an operation to insert a device into the hearing organ. This device can then use electricity to stimulate hearing on that side. For more information see here. This often gives the best possible hearing rehabilitation, and is the most effective way to treat tinnitus when it is caused by a severe hearing loss in the affected side.
References:
1. Evaluation of temporal and suprasegmental auditory processing in patients with unilateral hearing loss. Gürses E, Türkyılmaz MD, Kalaycıoğlu C, Karabulut E, Bajin MD, Sennaroğlu L, Genç GA. Auris Nasus Larynx. 2020 Oct;47(5):785-792.
2. The impact of permanent early-onset unilateral hearing impairment in children - A systematic review. Huttunen K, Erixon E, Löfkvist U, Mäki-Torkko E. Int J Pediatr Otorhinolaryngol. 2019 May;120:173-183.
3. Implantable Devices for Single-Sided Deafness and Conductive or Mixed Hearing Loss: A Health Technology Assessment. Ontario Health (Quality). Ont Health Technol Assess Ser. 2020 Mar 6;20(1):1-165.
4. Unilateral Cochlear Implants for Severe, Profound, or Moderate Sloping to Profound Bilateral Sensorineural Hearing Loss: A Systematic Review and Consensus Statements. Buchman CA, Gifford RH, Haynes DS, Lenarz T, O'Donoghue G, Adunka O, Biever A, Briggs RJ, Carlson ML, Dai P, Driscoll CL, Francis HW, Gantz BJ, Gurgel RK, Hansen MR, Holcomb M, Karltorp E, Kirtane M, Larky J, Mylanus EAM, Roland JT Jr, Saeed SR, Skarzynski H, Skarzynski PH, Syms M, Teagle H, Van de Heyning PH, Vincent C, Wu H, Yamasoba T, Zwolan T. JAMA Otolaryngol Head Neck Surg. 2020 Aug 27.