Signs of Hearing Loss
The signs of hearing loss can be subtle and emerge slowly, or early signs of hearing loss can be significant and come about suddenly. Either way, there are common indications and hearing impaired signs. You should suspect hearing loss if you experience any of the signs below.
You might have hearing loss if you . . .
- require frequent repetition.
- have difficulty following conversations involving more than 2 people.
- think that other people sound muffled or like they’re mumbling.
- have difficulty hearing in noisy situations, like conferences, restaurants, malls, or crowded meeting rooms.
- have trouble hearing children and women.
- have your TV or radio turned up to a high volume.
- answer or respond inappropriately in conversations.
- have ringing in your ears.
- read lips or more intently watch people’s faces when they speak with you.
- feel stressed out from straining to hear what others are saying.
- feel annoyed at other people because you can’t hear or understand them.
- feel embarrassed to meet new people or from misunderstanding what others are saying.
- feel nervous about trying to hear and understand.
- withdraw from social situations that you once enjoyed because of difficulty hearing.
- have a family history of hearing loss.
- take medications that can harm the hearing system (ototoxic drugs).
- have diabetes, heart, circulation or thyroid problems.
- have been exposed to very loud sounds over a long period or single exposure to explosive noise.
How We Hear
The Hearing System
The anatomy of the hearing system can be divided into four components for our convenience in remembering the parts and associating these parts with their function. These divisions are the:
- outer ear
- middle ear
- inner ear
- central auditory pathways
The Outer Ear
Several structures comprise the outer ear. The most readily seen is the pinna, also called the auricle. The pinna is made up of a frame of cartilage that is covered with skin. The pinna has obvious folds, elevations, depressions and a prominent bowl – all of which vary somewhat from person to person but a basic pattern in these features is fairly universal among all people. The pinna acts as a funnel to collect and direct sound down the ear canal. It also serves to enhance some sounds through its resonance characteristics. Finally, it helps us to appreciate front-back sound localization.
The other structure of the outer ear is the external ear canal. The outer two-thirds of this canal has a cartilaginous framework, and the inner one-third is bony. The skin of the external ear canal is continuous with the skin of the pinna. The ear canal is curved, almost “S” shaped and averages about 1 inch in length in adults. The skin of ear canal has hairs (more prominent in some people) and glands that produce wax called cerumen (also more prominent in some individuals than in others). This hair and cerumen serve a protective function for the ear canal. In addition, cerumen helps to lubricate the skin and keep it moist.
The Middle Ear
The middle ear begins at the inner end of the external auditory canal, specifically at the eardrum. Also called the tympanic membrane, the eardrum is a thin and delicate membrane stretched across the entire inner end of the ear canal separating the environment from the middle ear. Despite the delicacy of its structure, the tympanic membrane never stops working to transform fluctuations in air pressure known as sound into exact copies in the mechanical domain as vibrations.
On that inner side of the tympanic membrane is an air-filled space called the middle ear cavity. It contains the bones of hearing, two muscles, a number of ligaments, a small branch of the nerve of taste, and the opening of the Eustachian tube. The vibratory motions of the tympanic membrane are transmitted to the bones of hearing, also known as the ossicles or the ossicular chain. This ossicular chain articulates with the tympanic membrane through the lateral most bone called the malleus (hammer). The malleus then sends the mechanical vibrations to the incus (anvil), which in turn communicates with the inner most ossicle called the stapes (stirrup). These are the three smallest bones in the body, and, like the tympanic membrane, they never stop moving because they are constantly bombarded with sound, even while we’re sleeping! Functionally, the tympanic membrane converts the acoustical energy of sound into an exact copy in the mechanical domain. The ossiclesthen convey this mechanical energy to the inner ear at the oval window where the footplate of the stapes sits. It is at this location where the mechanical energy is then transformed into the hydraulic energy that the inner ear processes.
The ossicles are suspended from the roof of the middle ear cavity by tiny ligaments, and the malleus is connected to the tympanic membrane by a ligament, as well. In addition, there are two muscles located in the middle ear space. One is called the stapedius. It is attached to the stapes and contracts when very loud sounds are detected.
The opening for the Eustachian tube is located at the front wall of the middle ear cavity, and the other end opens in the upper, back part of the throat. The Eustachian tube is a muscular tunnel that opens and closes to provide fresh air to and drain debris from the middle ear space and to equalize the pressure between the environment and the middle ear space. It’s what we try to “pop” when we’re in an airplane, or an elevator, or in the mountains. Its functions are very important to maintaining the health of the middle ear space.
The Inner Ear
The inner ear has two divisions: one for hearing, the other for balance. The division for hearing consists of the cochlea and the nerve of hearing. The cochlea is snail-shaped, bony structure that contains three fluid-filled compartments that run the cochlea’s entire length. One compartment is sandwiched between the other two, and it contains the sensory organ for hearing called the organ of Corti. The organ of Corti responds when the hydraulic energy of the cochlear fluid activates its tiny hair cells to release chemical messengers. These messengers then stimulate the nerves of hearing which carry sound stimuli to the brain. The pitch and loudness of the original acoustic signal in the ear canal determine the exact location and the number of hair cells activated on the organ of Corti.
The balance mechanism is also called the vestibular system. It too is made up of a series of fluid-filled compartments (three semi-circular canals and two larger divisions) that contain the sense organs for balance and movement. The vestibular sensors detect angular movements, direction and velocity of the head. This information about equilibrium is sent to the brain by the vestibular nerves, a functionally separate division of the auditory vestibular nerve, the VIIIth cranial nerve.
Central Auditory Pathways
“Inner ear” is a collective term that encompasses the separate structures for hearing and balance. Once the auditory vestibular nerve reaches the brainstem, the balance system sends its information to brain structures responsible for processing this type of sensory information, whereas the hearing system sends its information to different parts of the brain specifically to extract the sound cues out of the electrical message brought by the nerves of hearing.
We can think of the central auditory pathways as being organized like circuits. There are short and long segments, all of which work together as the central auditory pathways or the central auditory nervous system. This system begins as the nerve of hearing enters the brainstem. From here, the neural pathway makes its way up to the cerebral cortex at the temporal lobe of the brain along the way switching back and forth from each side of the brainstem with neurons multiplying in number at each relay station along the circuit. Right ear information is directed to the left temporal lobe, and left ear information goes to the right temporal lobe. In addition, there is a transfer of information from one side of the brain to the other. In most people, the left side of the brain processes speech and other complex language functions, whereas tonal stimuli and music are deciphered by the right side of the brain.
The Process of “Hearing”
Our ears work to transform the acoustic stimulus that travels down our ear canals into the type of neural code that our brains can recognize, process and understand. It all starts at the tympanic membrane where the physical attributes of the sound are transformed into a mechanical stimulus. This mechanical code is transmitted through the ossicular chain to the stapes footplate where the code is again transformed this time into hydraulic energy for transmission through the fluid-filled cochlea. Finally, when the cochlea’s hair cells are stimulated by the fluid waves a neurochemical event takes place which excites the nerves of hearing. The physical characteristics of the original acoustic signal are preserved at every energy change along the way until this code becomes one that the central auditory pathways can direct to the temporal lobe of the brain for recognition and processing.
The brain and the relay stations along the central auditory pathways can extract not only the pitch and loudness features but also as other critical attributes such as temporal features (timing) and different cues from each ear. Features of the sound stimulus can be extracted, enhanced, and modulated and this information can be compared separately from each ear or combined into a single perception. These features can be compared to other acoustic patterns that are stored in the brain, perhaps for the recognition of the voice of a family member or friend, or they can be the initial experience with a new sound or a new voice.
Our hearing systems anchor us to the soundscape of our environment with an incredible ability to detect and differentiate infinitesimally small acoustic cues. Our brains store the neural equivalents of acoustic patterns – voices, music, environmental sounds, danger signals – that make it easier to process and recognize both familiar and unfamiliar signals. Hearing loss misleads our brain with a loss of audibility (sounds are softer, not as loud) as well as a distortion of the information that reaches the brain. Changes in the effectiveness of the brain to process stimuli, through head trauma, neurologic disease or disorder, or the naturally occurring process of aging, can result in symptoms that mimic hearing loss – inattention, inappropriate responses, confusion, a disconnect from the those around us, for example. The ears and the brain combine in a truly remarkable way to process neural events into the sense of hearing and all that it encompasses. Perhaps it’s fair to say that we “hear” with our brain, not with our ears!
Consequences of Hearing Loss
Many people are aware that their hearing has deteriorated but are reluctant to seek help. Perhaps they don’t want to acknowledge the problem, are embarrassed by what they see as a weakness, or believe that they can “get by” without using a hearing aid. And, unfortunately, too many wait years, even decades, to address the effects of hearing loss before getting treatment.
But time and again, research demonstrates the considerable effects of hearing loss on development as well as negative social, psychological, cognitive and health effects of untreated hearing loss . Each can have far-reaching implications that go well beyond hearing alone. In fact, those who have difficulty hearing can experience such distorted and incomplete communication that it seriously impacts their professional and personal lives, at times leading to isolation and withdrawal.
The Effects of Untreated Hearing Loss
Studies have linked untreated hearing loss effects to:
- irritability, negativism and anger
- fatigue, tension, stress and depression
- avoidance or withdrawal from social situations
- social rejection and loneliness
- reduced alertness and increased risk to personal safety
- impaired memory and ability to learn new tasks
- reduced job performance and earning power
- diminished psychological and overall health
Hearing loss is not just an ailment of old age. It can strike at any time and any age, even childhood. For the young, even a mild or moderate case of hearing loss could bring difficulty learning, developing speech and building the important interpersonal skills necessary to foster self-esteem and succeed in school and life.
Our mission is to help educate the public about hearing loss and promote the importance of prevention and treatment. On this website, you will find basic information about hearing loss, including advances in diagnosis and treatment, a review of different hearing aids, and resources for medical care and financial assistance.
If you think you or a loved one suffers from hearing loss, don’t delay another day. Visit a hearing healthcare professional and take the first step toward a world of better hearing.
Hearing Loss Types
A comprehensive audiologic evaluation must be completed in order to determine the types and severity of hearing loss to make appropriate recommendations for each patient. Pure tone and speech audiometry as well as the immittance test battery must be completed, in addition to any additional assessments necessary for an exhaustive profile of the hearing system. A balance test called electronystagmography (ENG) might also be needed if dizziness or imbalance is also a complaint. Some patients who are bothered by tinnitus only might have a complete tinnitus evaluation. Finally, the audiologic data provides a clinical foundation for recommendations on hearing aids and other assistive devices suitable for treating the types of hearing impairments listed below.
In general terms, there are two types of hearing loss, conductive and sensorineural. A combination of both is also seen as a mixed hearing loss. Each is discussed below.
Conductive Hearing Loss
Conductive hearing loss is caused by any condition or disease that impedes the conveyance of sound in its mechanical form through the middle ear cavity to the inner ear. A conductive hearing loss can be the result of a blockage in the external ear canal or can be caused by any disorder that unfavorably effects the middle ear’s ability to transmit the mechanical energy to the stapes footplate. This results in reduction of one of the physical attributes of sound called intensity (loudness), so the energy reaching the inner ear is lower or less intense than that in the original stimulus. Therefore, more energy is needed for the individual with a conductive hearing loss to hear sound, but once it’s loud enough and the mechanical impediment is overcome, that ear works in a normal way. Generally, the cause of conductive hearing loss can be identified and treated resulting in a complete or partial improvement in hearing. Following the completion of medical treatment for cause of the conductive hearing loss, hearing aids are effective in correcting the remaining hearing loss.
The audiometric profile that indicates a conductive hearing loss is the presence of air-bone gaps (better hearing by bone conduction than by air conduction), excellent word recognition at a comfortable listening level, and evidence of a middle ear dysfunction on immittance. For situations where a blockage is noted in the external ear canal, hearing testing is deferred until the canal is cleared.
Sensorineural Hearing Loss
The second type of hearing loss is called sensorineural hearing loss. This word can be divided into its two components – sensory and neural – to allow us more clarity in specifying the type of hearing loss. The comprehensive audiometric assessment and supplemental tests can yield the information needed to differentiate between a sensory and a neural hearing loss, although they can co-exist in the same ear. Neural hearing loss is another name for retrocochlear hearing loss.
Sensorineural hearing loss results from inner ear or auditory nerve dysfunction. The sensory component may be from damage to the organ of Corti or an inability of the hair cells to stimulate the nerves of hearing or a metabolic problem in the fluids of the inner ear. The neural or retrocochlear component can be the result of severe damage to the organ of Corti that causes the nerves of hearing to degenerate or it can be an inability of the hearing nerves themselves to convey neurochemical information through the central auditory pathways.
The reason for sensorineural hearing loss sometimes cannot be determined, it does not typically respond favorably to medical treatment, and it is typically described as an irreversible, permanent condition. Like conductive hearing loss, sensorineural hearing loss reduces the intensity of sound, but it might also introduce an element of distortion into what is heard resulting in sounds being unclear even when they are loud enough. Once any medically treatable conditions have been ruled out, the treatment for sensorineural hearing loss is amplification through hearing aids.
Mixed Hearing Loss
A mixed hearing loss can be thought of as a sensorineural hearing loss with a conductive component overlaying all or part of the audiometric range tested. So, in addition to some irreversible hearing loss caused by an inner ear or auditory nerve disorder, there is also a dysfunction of the middle ear mechanism that makes the hearing worse than the sensorineural loss alone. The conductive component may be amenable to medical treatment and reversal of the associated hearing loss, but the sensorineural component will most likely be permanent. Hearing aids can be beneficial for persons with a mixed hearing loss, but caution must be exercised by the hearing care professional and patient if the conductive component is due to an active ear infection.
What is an audiogram?
Hearing tests are usually carried out in an environment which is soundproofed from external noise. The person whose hearing is being tested listens to sounds transmitted by an audiologist and presses a button to signal when they have heard something. The results of the test are plotted on an audiogram.
Audiogram – measuring loudness and pitch
Volume The vertical axis represents volume (loudness) which is measured in decibels (dB). Sounds become louder from the top down – softest near the top of the graph.
Pitch The horizontal axis represents frequency (pitch) which is measured in hertz (Hz). Pitch goes from low (125Hz) on the left to high (8000Hz) on the right – similar to a piano (low notes on the left, higher to the right).
0 dB does not mean that there is no sound at all. It is simply the softest sound that a person with normal hearing ability would be able to detect at least 50% of the time. Normal conversational speech is about 45 dB
Different Level of Sounds from different sources and different sound from alphabets
Different severities of hearing loss
Normal hearing is when the softest sounds heard are between -10 and 20 dB. If the sounds are louder than 20 dB and you still can’t hear them, then there is a hearing loss. If the sounds are quieter than 20 dB and you cannot hear them, it may just be that your threshold of hearing is 20 dB. The further down the chart the line of your hearing test comes, the more of a hearing loss you have.
Mild hearing loss is between 21dB and 40dB. You often have difficulty following speech especially in noisy situations. This type of loss is often noticed by family first rather than yourself.
Moderate hearing loss is between 41dB and 70dB. You often have difficulty following speech and other quiet noises. Amplification can be very successful for this loss but you also need to use good hearing tactics (e.g. lipreading, expression, gesture).
Severe hearing loss is between 71dB – 95dB. You are unable to hear speech even in quiet surroundings and do not hear general noises such as traffic unless it’s loud. Amplification can be very successful for this loss but you need to use good hearing tactics (e.g. lipreading, expression, gesture). Lipreading classes will also be very useful if you have this hearing pattern.
Profound hearing loss is greater than 95dB. You are unable to hear most sounds unless really loud. Amplification is often useful but you need to rely on good communication tactics including lip-reading, subtitles on TV and possibly signing.
In the audiology clinic, when testing is done with headphones, we call them ‘air conduction thresholds’ as the sound must travel through the air of the ear canal to be heard.
Alternatively, hearing can be tested using a bone conductor – a device that rests on the bone behind the ear (held in place by a metal band stretching over the top of the head). This bone conductor transmits sound vibrations through the bones of the skull directly to the cochlea. This process allows the audiologist to test the hearing of the inner ear directly.
Right ear Sounds heard in the right ear are marked in red. When headphones are used (air conduction thresholds), they are marked with an O and when a bone conductor is used (bone conduction thresholds), they are marked with a [ or a triangle Δ.
Left ear Sounds heard in the left ear are marked in blue. When headphones are used (air conduction thresholds) they are marked with an X and when a bone conductor is used (bone conduction thresholds), they are marked with a ] or triangle Δ.
Sometimes the graphs of the each ear are plotted on separate audiograms, sometimes they are plotted on the same audiogram.
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