Hearing impairment, deafness, or hearing loss refers to the total or partial inability to hear sounds.
Symptoms may be mild, moderate, severe, or profound. A patient with a mild hearing impairment may have problems understanding speech, especially if there is a lot of noise around, while those with moderate deafness may need a hearing aid.
Some people are severely deaf and rely on lip-reading to communicate with others. People who are profoundly deaf can hear nothing at all and can find themselves totally reliant on lip-reading or sign language.
In the United States, around 15 percent of people over the age of 18 years report some level of hearing loss.
Causes
Some diseases or circumstances that can cause deafness to include:
- Chicken pox
- Cytomegalovirus
- Mumps
- Meningitis
- Sickle cell disease
- Syphilis
- Lyme disease
- As studies have shown that people with diabetes are more likely to have some kind of hearing loss,
- A treatment for tuberculosis (TB), streptomycin, is believed to be a key risk factor.
- Hypothyroidism
- arthritis
- Some cancers
- Teenagers exposed to second-hand smoke
The inner ear is home to some of the most delicate bones in the body, and damage to the eardrum or middle ear can cause hearing loss and deafness in a range of ways.
Hearing loss vs. deafness
It is important to distinguish between the different levels of hearing loss.
Hearing loss: This is a reduced ability to hear sounds in the same way as other people.
Deafness: This occurs when a person cannot understand speech through hearing, even when sound is amplified.
Profound deafness: This refers to a total lack of hearing. An individual with profound deafness is unable to detect sound at all.
The severity of hearing impairment is categorized by how much louder volumes need to be set at before they can detect a sound.
Some people define profoundly deaf and totally deaf in the same way, while others say that a diagnosis of profound deafness is the end of the hearing spectrum.
How does hearing work?
Sound waves enter the ear, move down the ear or auditory canal, and hit the eardrum, which vibrates. The vibrations from the eardrum pass to three bones known as the ossicles in the middle ear.
These ossicles amplify the vibrations, which are then picked up by small hair-like cells in the cochlea.
These move as the vibrations hit them, and the movement data is sent through the auditory nerve to the brain. The brain processes the data, which a person with functional hearing will interpret as sound.
Types
There are three different types of hearing loss:
1) Conductive hearing loss
This means that the vibrations are not passing through from the outer ear to the inner ear, specifically the cochlea. This type can occur for many reasons, including:
- An excessive build-up of earwax
- ear glue
- An ear infection with inflammation and fluid buildup
- A perforated eardrum
- malfunction of the ossicles
- A defective eardrum
Ear infections can leave scar tissue, which might reduce eardrum function. The ossicles may become impaired as a result of infection, trauma, or fusing together in a condition known as ankylosis.
2) Sensorineural hearing loss
Hearing loss is caused by dysfunction of the inner ear, the cochlea, auditory nerve, or brain damage.
This kind of hearing loss is normally due to damaged hair cells in the cochlea. As humans grow older, hair cells lose some of their function, and hearing deteriorates.
Long-term exposure to loud noises, especially high-frequency sounds, is another common reason for hair cell damage. Damaged hair cells cannot be replaced. Currently, research is looking into using stem cells to grow new hair cells.
Sensorineural total deafness may occur as a result of congenital deformities, inner ear infections, or head trauma.
3) Mixed hearing loss
This is a combination of conductive and sensorineural hearing loss. Long-term ear infections can damage both the eardrum and the ossicles. Sometimes, surgical intervention may restore hearing, but it is not always effective.
Deafness and speech
Hearing loss can affect speech ability depending on when it occurs.
Prelingual deafness
This is a condition in which a person is unable to hear totally or partially before learning how to say or interpret speech.
Prelingual deafness affects those who were born with a congenital abnormality or who lost their hearing during childhood.
People with prelingual deafness are more likely to have hearing parents and siblings. Many are also born into families where sign language is not spoken. As a result, they have a slower language development. Those who are born into signing families are less likely to experience linguistic delays.
Children with prelingual deafness who receive cochlear implants before the age of four can learn to communicate effectively.
The ability to use social cues and oral language are inextricably linked.
As a result, children with hearing loss, particularly those with severe symptoms, may endure delayed language as well as social development.
As a result, children with prelingual deafness are in danger of social isolation unless they attend a school with a well-run special needs department where they may interact with other children with the same condition.
Children who identify as part of a “deaf subculture” or who have learned sign language may feel less alone. However, if their parents have not yet learned sign language, some young persons may feel alone.
Due to their terrible deafness, some children with profound deafness find themselves on the outside of their hearing peers’ social groups, while others with utter deafness are not fully accepted.
Post-lingual deafness
Most people with hearing loss have post-lingual deafness. They acquired spoken language before their hearing was diminished. A medication side effect, trauma, infection, or disease may have caused losing their sense of hearing.
In most people with post-lingual deafness, hearing loss begins gradually.
Before they recognized the handicap, family members, friends, and teachers may have observed a problem. Hearing aids, a cochlear implant, or learning to lip-read may have been required depending on the severity of the hearing loss.
Hearing loss can provide a variety of issues depending on when it happens and how long it takes to develop. They may need to learn new technology, have surgery, learn sign language and lip-reading, and use a variety of communication gadgets.
Isolation is a prevalent problem that can lead to despair and loneliness in some people. A person with post-lingual hearing loss must also deal with the often-difficult process of accepting a disability.
Household members loved ones, and close acquaintances may have difficulties as a result of the condition, as they must adjust to the hearing loss.
Miscommunication can strain relationships, not just for the person with the hearing loss but also for others around them. Family members may incorrectly feel that the person with the illness is becoming more distant if the hearing loss is gradual and has not yet been detected.
Unilateral and bilateral deafness
Hearing loss in only one ear is referred to as single-sided deafness (SDD), whereas hearing loss in both ears is referred to as bilateral deafness.
If the other person is on their affected side, people with unilateral hearing loss may find it difficult to carry on a conversation. When compared to those who can hear well in both ears, pinpointing the source of a sound may be more challenging.
When there is a lot of background noise, it might be difficult to understand what others are saying. A person with unilateral deafness has nearly the same conversational abilities as someone who has a functional hearing in both ears when there is little to no background noise.
Unilaterally deaf babies are more likely to suffer developmental speech problems.
They may find it harder to concentrate when they go to school. Social activities may be more challenging than it is for children with no hearing problems.
Symptoms
The symptoms of hearing impairment depend on its cause. Some people are born without being able to hear, while others suddenly become deaf due to an accident or illness. For most people, symptoms of deafness progress gradually over time.
Some conditions may have hearing loss as a symptom, such as tinnitus or stroke.
Hearing impairment in infants
The following signs may indicate a hearing problem:
- The baby does not turn their head toward a noise until they are 4 months old.
- The baby has not spoken a single word at the age of 12 months.
- A loud noise does not appear to startle the infant.
- When the infant can see you, they answer well, but when you are out of sight and shout out their name, they respond much less or not at all.
- Only a few sounds appear to be heard by the baby.
Hearing impairment in toddlers and children
These signs might become more evident in slightly older children:
- The child is behind others the same age in oral communication.
- The child keeps saying “What?” or “Pardon?”
- The child talks in a very loud voice, and tends to produce louder-than-normal noises.
- When the child speaks, their utterances are not clear.
Four levels of deafness
There are four levels of deafness or hearing impairment. These are:
- A person with mild deafness or mild hearing impairment can only detect sounds between 25 and 29 decibels (dB). They may find it hard to understand the words other people are saying, especially if there is a lot of background noise.
- Moderate deafness or moderate hearing impairment: the person can only detect sounds between 40 and 69 dB. Following a conversation using hearing alone is very difficult without using a hearing aid.
- Severe deafness: The person only hears sounds above 70 to 89 dB. A severely deaf person must either lip-read or use sign language in order to communicate, even if they have a hearing aid.
- Profound deafness: anybody who cannot hear a sound below 90 dB has profound deafness. Some people with profound deafness cannot hear anything at all, at any decibel level. Communication is carried out using sign language, lip-reading, or reading and writing.
Diagnosis
Patients who suspect something is wrong with their hearing will initially go and see their doctor.
The doctor will talk to the patient and ask several questions regarding the symptoms, including when they started, whether or not they have gotten worse, and whether the individual is feeling pain alongside the hearing loss.
A physical examination
The doctor will look into the ear using an otoscope. This is an instrument with a light at the end. The following may be detected during the examination:
- a blockage caused by a foreign object
- a collapsed eardrum
- an accumulation of earwax
- an infection in the ear canal
- an infection in the middle ear if a bulge is present in the eardrum.
- cholesteatoma, a skin growth behind the eardrum in the middle ear.
- fluid in the ear canal
- a hole in the eardrum
The doctor will ask questions about the person’s experiences with hearing, including:
- Do you have a habit of asking individuals to repeat themselves?
- Do you have trouble understanding folks on the phone?
- When the doorbell rings, do you miss it? Is this something that happens frequently?
- Do you have to concentrate when you’re having a face-to-face conversation?
- Has anyone ever suggested to you that you could have a hearing problem?
- Do you notice that people today mumble more than they used to?
- When you hear a sound, do you ever have trouble figuring out where it’s coming from?
- Do you have trouble understanding what one of numerous people is saying when there are several others talking?
- Have you ever been told that the TV, radio, or any other sound-producing gadget is too loud?
- Do you find it simpler to comprehend masculine voices than female sounds?
- Do you spend the majority of your waking hours in a noisy environment?
- Have you ever had the experience of misinterpreting what other people say to you?
- Do you hear sounds like rushing, hissing, or ringing?
- Do you shy away from group discussions?
If you answered “yes” to most of the above questions, see a doctor and have your hearing checked.
General screening test
A doctor may ask the patient to cover one ear and describe how well they hear words spoken at different volumes, as well as checking sensitivity to other sounds.
If the doctor suspects a hearing problem, they will probably be referred to either an ear, nose, and throat (ENT) specialist or an audiologist.
Further tests will be carried out, including:
A tuning fork test: this is also known as the Rinne test. A tuning fork is a metal instrument with two prongs that produce a sound when it is struck. Simple tuning fork tests may help the doctor detect whether there is any hearing loss and where the problem is.
A tuning fork is vibrated and placed against the mastoid bone behind the ear. The patient is asked to indicate when they no longer hear any sound.
The fork, which is still vibrating, is then placed 1 to 2 centimeters (cm) from the auditory canal. The patient is asked again whether they can hear the fork.
As air conduction is greater than bone conduction, the patient should be able to hear the vibration. If they cannot hear it at this point, it means that their bone conduction is superior to their air conduction.
This suggests a problem with sound waves getting to the cochlea through the ear canal.
Audiometer test: The patient wears earphones, and sounds are directed into one ear at a time. A range of sounds is presented to the patient in various tones. The patient has to signal each time a sound is heard.
Each tone is presented at various volumes so that the audiologist can determine at which point the sound of that tone is no longer detected. The same test is carried out with words.
The audiologist presents words at various tones and decibel levels to determine where the ability to hear stops.
Bone oscillator test: This is used to find out how well vibrations pass through the ossicles. A bone oscillator is placed against the mastoid. The aim is to gauge the function of the nerve that carries these signals to the brain.
Routine screening of children
The American Academy of Pediatrics (AAP) recommends that children have their hearing tests at the following times:
- when they start school
- at 6, 8, and 10 years of age
- at least once when they are in middle school
- once during high school
Testing newborns
The otoacoustic emissions (OAE) test involves inserting a small probe into the outer ear; it is usually done while the baby is asleep. The probe emits sounds and checks for “echo” sounds bouncing back from the ear.
If there is no echo, the baby might not necessarily have a hearing problem, but doctors will need to carry out further tests to make sure and to find out why
Treatment
Help is available for people with all types of hearing loss. Treatment depends on both the cause and severity of the deafness.
Sensorineural hearing loss is incurable. When the hair cells in the cochlea are damaged, they cannot be repaired. However, various treatments and strategies can help improve the quality of life.
Hearing aids
These are wearable devices that assist hearing.
There are several types of hearing aid. They come in a range of sizes, circuitries, and levels of power. Hearing aids do not cure deafness but amplify the sound that enters the ear so that the listener can hear more clearly.
Hearing aids consist of a battery, loudspeaker, amplifier, and microphone. Today, they are very small, discreet, and can fit inside the ear. Many modern versions can distinguish background noise from foreground sounds, such as speech.
A hearing aid is not suitable for a person with profound deafness.
The audiologist takes an impression of the ear to make sure the device fits well. It will be adjusted to suit auditory requirements.
Examples of hearing aids include:
Behind-the-ear (BTE) hearing aids: These consist of a dome called an earmold and a case, with a connection linking one to the other. The case sits behind the outer ear, with the connection to the dome coming down the front of the ear. The sound from the device is either electrically or acoustically routed to the ear.
BTE hearing aids tend to last longer than other devices, as the electrical components are located outside the ear, meaning that there is less moisture and earwax damage These devices are more popular with children who need a sturdy and easy-to-use device.
In-the-canal (ITC) hearing aids: These fill the outer part of the ear canal and can be seen. Soft ear inserts, usually made of silicone, are used to position the loudspeaker inside the ear. These devices fit most patients straight away and have better sound quality.
Completely in the canal (CIC) hearing aids: These are tiny, discreet devices but not recommended for people with severe hearing loss.
Bone conduction hearing aids: These assist people with conductive hearing loss, as well as those unable to wear conventional type hearing aids. The vibrating part of the device is held against the mastoid with a headband. The vibrations go through the mastoid bone, to the cochlea. These devices can be painful or uncomfortable if worn for too long.
Cochlear implants
A cochlear implant may be beneficial if the eardrum and middle ear are in good working order.
The cochlea is pierced with this thin electrode. It works by stimulating electricity through a tiny microcontroller hidden behind the ear.
A cochlear implant is used to aid individuals whose hearing loss is caused by cochlear hair cell destruction. Speech comprehension is frequently improved by the implants. New technology in the latest cochlear implants allows patients to enjoy music, hear speech better even in noisy environments, and utilize their processors while swimming.
According to the National Institutes of Health (NIH), roughly 58,000 adults and 38,000 children in the United States had cochlear implants in 2012. According to the World Health Organization (WHO), around 219,000 people are affected.
On the outside, a cochlear implant consists of:
- A microphone collects sound from the surrounding area.
- A speech processor is a device that prioritises sounds important to the patient, such as speech. The electrical sound signals are separated into channels and transmitted to the transmitter through a very tiny wire.
- A transmitter is a coil that is held in place by a magnet. It is placed behind the ear and sends the processed sound signals to the device that is implanted inside the ear.
On the inside:
- A surgeon secures a receiver and stimulator in the bone beneath the skin. The signals are converted into electrical impulses and sent through internal wires to the electrodes.
- Up to 22 electrodes are wound through the cochlea. The impulses are sent to the nerves in the lower passages of the cochlea and then directly to the brain. The number of electrodes depends on manufacturers of the implant.
Children will usually have cochlear implants in both ears, while adults tend to have just one.
Sign language and lip-reading
Some people with hearing impairment may have speech problems, as well as difficulties in understanding speech from other people.
A high percentage of people with hearing impairment can learn other ways of communicating.
Lip reading and sign language can replace or complement oral communication.
There is a range of sign languages that are, in some cases, wildly different from one another.
Lip reading
Also known as speechreading, lip reading is a method for understanding spoken language by watching the speaker’s lip, facial, and tongue movements as well as extrapolating from the data provided by the context and any residual hearing the patient might have.
People who became hearing impaired after they learned to speak can pick up lip reading rapidly; this is not the case for those who are born hearing-impaired.
Sign language
This is a language that uses signs made with the hands, facial expressions, and body postures, but no sounds. It is used mainly by those who are deaf.
There are several different types of sign languages. British Sign Language (BSL) is very different from American Sign Language (ASL). For instance, BSL uses a two-handed alphabet, whereas American sign language uses a one-handed alphabet.
Some countries use the sign language introduced by missionaries from far away. Norwegian sign language, for example, is used in Madagascar.
Sign language is completely different from the spoken form, word order, and grammar in BSL is not the same as it is in spoken English. ASL is more grammatically similar to spoken Japanese than spoken English.
Prevention
Nothing can prevent the hearing problems that occur from birth or hearing impairments due to illnesses or accidents.
However, some measures can be taken to reduce the risk of losing some of your senses of hearing.
The structures in the ears can be damaged in several different ways. Long-term exposure to noise above 85 dB – the volume of a typical lawnmower – can eventually cause hearing loss.
The following measures may help protect your hearing:
- TV, radio, music players, and toys: Do not set the volume too high. Children are especially sensitive to the damaging effects of loud music. Noisy toys can put children’s hearing at risk.
- Headphones: Focus on isolating the sounds you want to hear and blocking out as much environmental sound as is possible, instead of drowning it out with high volume.
- Occupational health: If you work in a noisy environment, such as discos, nightclubs, and pubs, wear earplugs or earmuffs.
- Leisure venues: If you go to pop concerts, motor racing, drag racing, and other noisy events, wear earplugs.
- Cotton swabs: Do not prod them into adult or infant ears. The same applies to Q-tips or tissues.
Hearing can often deteriorate with age, but the risk can be reduced by taking the correct preventive measure early on.