What Is Sudden Hearing Loss
Sudden hearing loss occurs when there is a total or partial loss of hearing in one or both ears. This loss can be conductive in nature (meaning it is caused by a problem in the outer or middle ear) or it can be sensorineural in nature (meaning it is caused by a problem in the cochlea or the auditory nerve). Sudden conductive hearing loss may be caused by impacted ear wax or a middle ear infection. Sudden sensorineural hearing loss may be caused by inflammation or a virus in the inner ear. The treatment for sudden hearing loss depends on the cause, and it is important to seek medical treatment from an audiologist or an ear, nose, and throat physician right away. The sooner the sudden hearing loss is treated, the more likely that the hearing will improve.
How Common Is Hearing Loss In One Ear?
Hearing loss in one ear is called unilateral hearing loss. The hearing loss can range from mild to profound or total deafness. It can be present at birth or it can occur later in life. Statistics show that approximately 1 in 1000 babies are born with unilateral hearing loss and that approximately 7% of adults in America have unilateral hearing loss. The National Institutes of Health reports that the prevalence of hearing loss for all adults in the United States is 13%, so unilateral hearing loss makes up approximately half of the total cases. The incidence of hearing loss increases as we age, and is reported at 25% for those age 65 and older and 50% incidence for those age 75 and older.
How Hearing Loss Can Occur
There are many causes of hearing loss. Babies can be born with hearing loss in one or both ears. Hearing loss present at birth can be caused by genetic mutations, the mother’s exposure to or consumption of toxins, or developmental concerns in utero. Hearing loss can begin at any age and becomes more common as we get older. Hearing loss can be categorized as conductive or sensorineural hearing loss. Conductive hearing loss occurs when there is a problem with the outer ear (ear canal or eardrum) or middle ear (middle ear bones, middle ear cavity, or eustachian tube) that prevents the sound from traveling to the inner ear. A gradual buildup of earwax in the ear canal can cause conductive hearing loss. A viral, bacterial, or fungal infection in the ear canal can also cause conductive hearing loss. This is called otitis externa which is just a fancy name for an outer ear infection. A ruptured eardrum (tympanic membrane perforation) can be caused by trauma, such as a blow to the ear or a cotton swab inserted too deeply. It can also be caused by too much pressure in the middle ear. Tympanic membrane perforations can cause conductive hearing loss. Middle ear issues that cause conductive hearing loss include middle ear infections, clogged eustachian tubes, and abnormal bone growths or tumors that can occur on the eardrum (tympanic membrane), on the middle ear bones, or in the middle ear cavity. Sensorineural hearing loss is caused by damage to the cochlea (organ of hearing) or to the eighth cranial nerve (hearing nerve). This damage can be caused by noise exposure, inflammation, toxins, viral or bacterial infections, and the normal aging process. Sensorineural hearing loss often affects high frequency hearing more than low frequency hearing, so higher-pitched tones may gradually become muffled.
How Hearing Loss In One Ear Affects Hearing
Hearing loss in one ear (unilateral hearing loss) can be quite problematic for people of all ages and can present significant challenges, particularly for school-age children. Unilateral hearing loss causes three main hearing problems.
First, it makes the volume of all sounds softer. When we have two normally-functioning ears, the two ears work together to provide a boost in volume. When one ear isn’t hearing normally, we don’t get that helpful volume boost.
Second, unilateral hearing loss makes it more difficult to hear in noisy situations. Busy restaurants, bars, classrooms, or playgrounds can be challenging, even for people with normal hearing. However, when we have two normally-functioning ears, the two ears work together to help us pick out speech signals from the surrounding noise. The brain processes the sound coming from both ears and is able to “tune out” the background noise and focus more on the speech that we want to hear. When one of our ears isn’t functioning properly (due to unilateral hearing loss), the brain is only receiving input from the good ear and it isn’t able to distinguish the speech signal from the surrounding noise. Therefore, people with unilateral hearing loss often have a very difficult time hearing in situations with lots of background noise.
The third way that unilateral hearing loss affects our hearing is by impairing our ability to determine which direction a sound is coming from. This is called localization. When we have normal hearing in both ears, the two ears work together to identify where the sound is coming from. If a dog barks behind you and slightly to the right side, your right ear will pick up the sound a split second before your left ear which tells the brain that the sound is on your right side. You then know to look to your right in order to see the dog. When we have unilateral hearing loss, this localization function cannot work properly because the brain is only receiving the full sound input from one side. It doesn’t have another point of reference, and therefore cannot tell us which direction the sound is coming from. This can be dangerous in certain situations, such as when we are driving and hear a siren coming towards us. Unilateral hearing loss can be particularly challenging for children in school as they are tasked with hearing, understanding, and remembering what they are taught in a sometimes noisy environment with teachers who often walk around the classroom while lecturing.
The ‘Head Shadow’ Effect Of Single-Sided Deafness
The head shadow effect is caused by single-sided deafness, with the head acting as a barrier preventing sound from reaching the good ear. For example, if I have partial or total loss of hearing in my left ear, sounds coming from my left side have to travel over or around my head in order to be picked up and processed by my good right ear. This results in a delay as well as a reduction of volume, and it affects our ability to determine which side sounds are coming from (localization) as well as our ability to hear in noisy situations.
Causes Of Hearing Loss In One Ear
Hearing loss in one ear (unilateral hearing loss) can be caused by a buildup of cerumen (earwax) in the ear canal, or an infection in the ear canal. It can also be caused by problems with the eardrum, such as a perforation or an abnormal bony growth on the eardrum or middle ear bones. Middle ear infections can cause unilateral hearing loss as well. Inner ear causes of unilateral hearing loss include abnormal pressure in the cochlea (cochlear hydrops), inflammation or infection of the inner ear, or genetic conditions.
Sudden Hearing Loss In One Ear
Sudden hearing loss in one ear is most often caused by earwax buildup or middle ear infections. It can also be caused by a problem in the inner ear, such as a viral infection or inflammation. Sudden unilateral hearing loss is often accompanied by other symptoms, such as ringing in the ear (tinnitus), pressure in the ear, or dizziness. It is important to seek medical treatment from an audiologist or physician as soon as possible in order to prevent or reduce permanent hearing loss.
Treatment Options For Single-sided Deafness
There are two excellent treatment options for people who have single-sided deafness. The first option is a CROS system. CROS stands for “contralateral routing of sound,” and consists of two devices that are worn on the ears just like hearing aids. They typically come in a behind-the-ear style of hearing aid. CROS systems are used by people who have no hearing in one ear and normal hearing in the other ear. The device that sits on their deaf ear consists of a microphone and a transmitter. It picks up the sound on that side and transmits it to the receiver device that sits on the normal hearing ear. This device receives the transmitted sound and delivers it to the normal hearing ear. BiCROS is another option for single-sided deafness. BiCROS stands for “bilateral contralateral routing of sound,” and these systems are used by people who have some degree of hearing loss in their good ear. The receiver that sits on the good ear is also a hearing aid, and so it not only receives the sound from the transmitter worn on the deaf ear, but it also amplifies the sound to the appropriate level so that the user can hear it clearly.
Bone-anchored hearing aids (BAHAs) are another option for people with single-sided deafness. These systems utilize bone conduction to transmit sound to the normal hearing cochlea. A small titanium fixture is surgically implanted behind the deaf ear and a small processor connects to this fixture. The processor picks up sound from that side and transmits those soundwaves through the implanted titanium fixture via direct bone conduction (rather than via the middle ear system). This enables the normal-hearing cochlea to process the sounds coming from the side of the deaf ear. BAHA systems can also be used for people who have malformations of their outer ear which prevent them from wearing a traditional hearing aid or CROS device, or by those who have chronic middle ear infections or drainage that would prevent them from wearing a device that goes into their ear canal.
