Hearing Loss

Hearing is one of our five senses (touch, smell, taste, sight, and hearing). A reduction in hearing ability is called a hearing loss or hearing impairment. There are approximately 500 million people worldwide with some form of hearing loss. It is estimated that this phenomenon is supposed to grow to 700 million by the year 2015. Increasing amounts of noise in today’s environment seems to be the main factor in this skyrocketing number. Due to the fact that noise, not age is the primary contributing factor in hearing loss, it is not surprising that 50% of all hearing loss takes place in people under the age of 65 years old.

Hearing loss is a common occurrence. The sounds around us are perceived by our hearing system 24 hours a day. Hearing is not a sense that you can ‘turn off’. Our hearing works at several levels: With our hearing we perceive background sounds, such as traffic noise, or more relevant sounds, such as the ringing of an alarm clock. What is generally most important is, however, the ability to hear speech- to communicate. Our hearing system must be able to distinguish among a multitude of sounds – from the soft rustle of leaves to complex sentences. When our hearing ability is reduced, we are no longer able to hear sounds optimally.

How We Hear

The ear consists of three parts: the outer, middle and inner ear. All three parts work together to deliver sound information to the brain where it is interpreted as hearing. The outer ear consists of the visible part of the ear (pinna or auricle) and the ear canal. The outer ear picks up sounds from the environment and transmits the sound waves down the ear canal to the ear drum. The middle ear is comprised of the ear drum (tympanic membrane), which is connected to three tiny bones (ossicles). The sound waves cause the ear drum to vibrate, which sets the ossicles –the malleus (hammer), incus (anvil) and stapes (stirrup)- into motion. The inner ear is comprised of two main fluid filled parts: the cochlea, which contains the intricate hair cells (sensory cells); and the vestibular system (controls balance). The motion from the stapes bone connected to the cochlea causes the fluid in the cochlea to move or create waves and in turn causes the tiny hair cells to move. The hair cells absorb the movement and change it into electrical impulses that are transferred to the auditory nerve fibers. The electrical impulses are then sent through the auditory nerve to the brain where they are interpreted as sound.

Please see the animation below for a visual representation and diagram.

Hearing and Hearing Loss - Normal Hearing, Hearing Loss, Aided Hearing and Cochlear Implant Aided Hearing. Cochlear Implantation - The implant is placed behind and above the ear and secured. A mastoidectomy is needed for access to the inner ear. An opening in the cochlea (called a cochleostomy) is created and the electrode is inserted into the cochlea. View the animation to the right to learn more about how we hear and the implant surgery.

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There are three main categories of hearing loss; conductive, sensorineural, and mixed.

  • Conductive hearing loss occurs when the problem lies in the outer or middle ear and sound is therefore blocked from or reduced before getting to the inner ear. Examples of conductive hearing losses in the outer ear can be as simple as wax (cerumen) plugging up the ear canal, a cyst growing in the ear canal or a congenital malformation known as atresia (the ear canal was not formed during gestation and is therefore closed off) or microtia (abnormal appearance or lack of the external ear- the pinna). Examples of conductive hearing losses of the middle ear can include fluid in the middle ear space (ear infections that children typically get), a perforation of the ear drum or otosclerosis where the joints of ossicles of the middle ear stiffen and no longer vibrate as effectively. Conductive hearing loss is sometimes temporary and can occasionally be addressed medically or by surgery.
  • Sensorineural hearing loss occurs when the auditory nerve or the cochlea itself is damaged. This is the type of hearing loss we see due to aging (presbycusis) or from noise induced hearing loss. Noise induced hearing loss can be a temporary or permanent decrease in hearing due to sudden impulse sounds like gun fire or prolonged loud noise exposure like concerts or a lifetime of hunting.
  • A mixed hearing loss occurs when there is a combination of both a sensorineural component and a conductive component. For example, if someone with typical age related sensorineural hearing loss also gets and ear infection (fluid in the middle ear) or a plug of wax in their ear canal, they would have a conductive hearing loss component on top of their sensorineural hearing loss. For patients with mixed hearing losses, the conductive component of that loss is sometimes temporary and can occasionally be addressed medically or surgically.

Causes of Hearing Loss

In about 50% of children and adolescents suffering from hearing loss, that loss has been present since birth. The causes of hearing loss are often unknown, but if the hearing loss has been present since birth, there could be a genetic cause, or it could be connected with problems during pregnancy or childbirth, or premature births.

If the child or adolescent becomes hearing impaired after birth, the cause could be trauma or sickness. Meningitis commonly causes hearing loss, with about one-third of afflicted children suffering some kind of hearing impairment.

Genetic Problems

Hearing impairment caused by genetic problems may be part of a “syndrome” that includes other symptoms. For example, Waardenburg syndrome is associated with hearing loss and is characterized by a wide spacing between the eyes, broad nose bridge, and connecting eye brows. Changes in the eyes and hair can also be present. The deafness caused by Waardenburg syndrome can vary from mild to total. It is present from birth and is non-progressive.

Crouzon syndrome is a genetic condition that causes the plates of the skull to become fused, preventing growth of the brain and causing deformities of the face. It is associated with deformity of the inner ear, or even complete absence of ear canals.

A genetic cause of hearing loss not associated with a syndrome is the connexin 26 gene. Connexin genes are important in the development of hair cells in the cochlea, and a mutation in this gene is the most common non-syndromic genetic cause of deafness.

Deafness caused by connexin 26 is characterized by profound loss of hearing from birth, and not accompanied by other symptoms such as blindness. Newborn infants with confirmed deafness can be tested for connexin 26 (also known as GJB2). If both parents carry the connexin 26 gene, their baby will have a 25% chance of being born deaf.

Complications During Pregnancy

Some illnesses contracted during pregnancy are associated with hearing problems in infants. German measles, syphilis and diabetes all show a high risk to the unborn baby. Some medications are also dangerous for the unborn child. Ototoxic medicines, that is, medicines that cause damage to the ear, could be a major source of hearing loss in new-born children.

It is not always clear which drugs are ototoxic – the same drug can have varying ototoxic properties in different people. Always be very careful about taking medication while pregnant, and if you become sick during pregnancy, make sure that the consulting doctor knows that you are pregnant.

Premature babies are often at risk for developmental problems including hearing loss. The myriad of problems that a premature baby faces puts a strain on the baby’s immune system. Often the lungs are undeveloped, necessitating the use of a ventilator. Excessive ventilator use is associated with lung infections that can spread to the ear canal.

A premature baby may also need to the receive nourishment intravenously or through a tube that passes through the nose and into the stomach. All these procedures place the baby at an increased risk for infection which may ultimately affect the hearing.

Trauma during birth may also play a factor in infant hearing loss. Large babies, babies with an oversized cranium or a breeched fetus can indicate a difficult delivery that may injure the baby. Such trauma, especially to the head, may cause hearing loss.

Conductive Hearing Loss

Conductive hearing loss refers to a blockage in the ear canal, preventing sound from passing from the outer ear to the inner ear. This usually causes temporary hearing loss, and when the cause is removed, the hearing usually returns to normal.

Temporary hearing loss is very common throughout childhood, and the most common cause is upper respiratory infection. This causes an accumulation of fluid in the middle ear, which, if it cannot drain, will affect the ability of the ear drum to vibrate, reducing the ability to hear.

Common colds can be another cause for hearing loss. A heavy cold can cause the pressure on the ear drum to become imbalanced, preventing it from vibrating.

Another common cause of conductive hearing loss is the build-up of wax in the ear. A doctor can remove the excess wax by flushing it out with water, using a special suction vacuum, or removing it with forceps.

Congenital conductive hearing loss in children can be caused by anatomic abnormalities of the outer and middle ear including congenitally fixed stapes, aural atresia (lack of an ear canal), stenosis (constricted ear canal), and microtia (missing or deformed outer ear). All of these conditions have the potential of surgical correction once the child reaches at least three years of age.

Acquired Hearing Loss - Permanent

Permanent hearing loss can happen at any time of life. Although we associate hearing loss with aging, children can also lose their hearing through a number of causes.

Diseases like chicken pox and measles, if severe enough and not properly attended to, have been connected with permanent hearing loss. Encephalitis is another disease with a very strong link to hearing loss. Head injury or noise trauma can be another cause.

Common ear infections, if left untreated, can lead to permanent hearing loss. Otitis media is an extremely common childhood condition. This is an inflammation of the inner ear that may cause fluid build-up. Usually the condition will clear up with no permanent affect on hearing, but repeated episodes of otitis media may cause damage to the ear drum and hearing nerves.

Enlarged Vestibular Aqueducts

One possible cause for progressive hearing loss in children is enlarged vestibular aqueducts. The vestibular aqueducts are narrow passages that connect the inner ear with the cranium. In normal adults, the vestibular aqueducts are narrow, “J” shaped tubes, but in new born babies they are straight and much wider. As the child grows, the tube becomes thinner and takes on the “J” shape found in adults.

In some children, however, the tube remains wide, and this condition is known as Enlarged Vestibular Aqueducts Syndrome (EVAS). The cause is unknown, but does occasionally appear to be genetic and run in families.

If your child is experiencing progressive hearing loss, he can be tested for EVAS by a CT scan. This will give your doctor detailed information about the anatomical structure of your child’s inner ear. If diagnosed with EVAS, the doctor may suggest avoiding sports, as head trauma could lead to an increase in hearing loss.


Ear infections and other ear-related injuries can lead to permanent hearing loss . Any change in your child’s hearing should be immediately attended to. Untreated hearing loss is associated with:

  • Twice as many visits to the emergency room
  • A ten times higher chance of being kept back a grade at school
  • Reduced earning potential as an adult
  • Mis-diagnosis as ADHD

Always consult a doctor as quickly as possible. Your best choice would be to seek out an otologist (an ENT who specializes in only ear related disorders) with a strong pediatric practice. State of the art diagnostics, combined with the selection of appropriate hearing aids and skilled, professional programming and fitting, like that provided by the audiologists at the Hearing Device Center of the California Ear Institute, combined with assistive listening devices and acoustical modifications may also necessary to creating the optimal listening environment for a hearing impaired child. Click here to make an appointment to improve your hearing today !

For more information, please refer to these web sites:

The National Deaf Children's Society
The American Speech-Language-Hearing Association
The American Academy of Pediatrics

Common Causes Of Hearing Impairment In Seniors- Introduction

Hearing loss is a natural consequence of aging. One in four people over the age of 60 have measurable hearing loss. Over the age of 70, the numbers jump to one in two. The older we get, the more likely it will be that we will experience some hearing impairment.

Types of Hearing Loss

When we talk about hearing loss, it’s important to distinguish the type. The three main types of hearing loss are conductive, sensorineural and central. The type of hearing loss will determine which kind of treatment is most suitable.

Conductive hearing loss refers to an interruption in the transmission of sound from the outer ear to the inner ear. One reason for this could be an obstruction in the ear canal by wax or some other substance. A loss in mobility of the ear drum, perhaps due to a build up of fluid, could be another cause. A cause that is specific to older individuals is Otosclerosis, that is, arthritis of the middle ear bones.


Ear wax build-up is a very common cause of hearing loss. Ear wax (cerumen) is produced by glands in the ear canal. Its function is to trap dust and dirt and prevent it from damaging the ear. Excess wax usually dries and falls out during normal washing, but some people produce wax faster than it can be excreted, causing a build up which eventually blocks the ear canal. The result is temporary hearing loss, which, fortunately, can be easily remedied by flushing the ear canal with warm water.

Infections are another reason for the ear canal to become blocked. Infections may cause the ear drum to become red and swollen, and fluid may get trapped in the ear canal.

People with conductive ear loss often say that their own voice sounds loud while other voices are muffled. They may also experience ringing in the ears.

Conductive hearing loss can usually be corrected with medicine or surgery. If neither of these methods help, hearing aids are very useful for this condition, because the patient simply needs sound to be amplified because the auditory nerve is still functioning well.


The hair cells of the cochlea in the inner ear are susceptible to damage from many causes. Long term noise exposure, diseases causing ear infection and head trauma can damage the delicate hair cells. Causes of nerve damage include tumors and disease such as multiple sclerosis. Some medications are referred to as “ototoxic” because they are associated with hair cell damage. These include some chemotherapy drugs, antibiotics, diuretics, and pain killers in extremely large quantities.

A person with sensorineural hearing loss may have a loss of hearing in only part of the sound spectrum. Frequently, older individuals with sensorineural hearing loss have worse hearing in the higher frequencies than the lower frequencies. Modern digital hearing aids are extremely beneficial for this condition because they can amplify just the parts of the sound spectrum that have been lost, while filtering out background noise.

To identify the nature of your hearing loss, an audiologist will measure your ability to hear various frequencies at different intensities. Using this information, the audiologist can suggest treatment options such as which type of hearing aid will be the most useful. Family members may also be trained to recognize which sound environments may cause difficulty, and perhaps the acoustics of the home can be changed to eliminate problems such as echoes.


Much of the hearing loss we experience in later years can be connected to previous events or trauma. In order to minimize hearing loss, prevention is the best solution. Everybody at every age should be aware of what can cause hearing loss and try their best to avoid situations that can damage their hearing, or at least to protect their ears and their hearing as much as possible.


When working in a noisy environment, always wear ear protection The accumulated effect of noise over a lifetime should not be overlooked. Common household tasks like cutting the lawn should always be performed with ear protectors. When listening to music on a personal music system, always keep the volume low enough to prevent future hearing loss.

Overall Health

Maintaining overall good health is good for your hearing. Healthy eating habits and a regular exercise regimen will improve all aspects of your life. Regular medical checkups can help catch health problems before they cause long term damage. If there is a history of hearing loss in your family, be sure to schedule annual exams to monitor your hearing.

State of the art diagnostics, combined with the selection of appropriate hearing aids and skilled, professional programming and fitting, like that provided by the audiologists at the Hearing Device Center of the California Ear Institute, combined with assistive listening devices and acoustical modifications may help create the optimal listening environment for any hearing impaired senior. Click here to make an appointment to improve your hearing today !

For more information about hearing loss, visit this web site:

National Institute on Deafness and Other Communication Disorders

How We Test for Hearing Loss

An audiogram is a graphic representation of audiometric data. It is a picture of your hearing ability. The audiogram is used because it provides a convenient way to visualize hearing ability on a scale related to the “normal” range of hearing. The vertical lines on an audiogram represent pitch or frequency. Low frequencies start on the left side of the graph and each line to the right represents a higher frequency. Moving from left to right on an audiogram would be consistent with moving from left to right on a piano (low to high pitches). The horizontal lines on an audiogram represent loudness or intensity. The zero decibel (dB) line is located at the top of the audiogram and represents a barely audible sound. Each line below represents a louder and louder sound. During the hearing test, the Audiologist will try to determine your threshold for hearing, or the softest sound you can hear. At each test frequency, your threshold will be marked on the audiogram at the softest level that you respond reliably.

Description of Hearing Test:

The objective of any hearing test is to measure the threshold (the softest you can detect sounds) for tones and speech. During the hearing test, the Audiologist will place foam earphones in each ear and a headband around your forehead to hold a bone conductor in place. The earphones deliver sound through the air (sound waves) and the bone conductor delivers sound through small bone vibrations. You will most likely not feel the vibration of the bone conductor during the test. When we hear through air conduction, we are testing all the parts of the ear. When we test through bone conduction, we are bypassing the outer and middle ear and directly stimulating the inner ear, the cochlea. We compare the air conduction thresholds to the bone conduction thresholds to determine which part(s) of the ear is responsible for the hearing loss. When the test starts, you will be instructed to respond each time you hear a soft tone presented in either ear. In addition, you may occasionally hear a static noise in the background of either ear that should be ignored. This is called masking noise and is used to isolate one ear at a time for accurate measurements. The Audiologist will measure your threshold for tones over a range of frequencies(or pitches). Typically, the range is 250 to 8000 Hz because this encompasses the frequency range necessary to understand speech. Speech testing includes two tests. First, the Speech Reception Threshold (SRT) test is used to measure the lowest level at which you can repeat words. It is common to use two-syllable words with equal stress on each word for the SRT. The second speech test, Speech Discrimination (SD), is used to assess your ability to understand and repeat single-syllable words presented at a loud volume. The SD test is beneficial because it tells us how your auditory system and brain are processing the incoming sound and measures the amount of speech distortion you may be experiencing. At the conclusion of the hearing test, the audiologist will review the results and recommendations and answer any questions you may have about the test.

Loudness Scale

Listed below on the left are several common sounds with the corresponding decibel (dB) output listed on the right. All values are approximations.

Whisper 30
Normal Conversation, Dishwasher 60
Vacuum Cleaner 70
Subway, Busy Street 80
Lawn Mower 90
Chain Saw, Snow Mobile 100
Rock Concert 120
Jackhammer 130
Gunfire, Jet Engine 140
Rock Music, Peak 150

Types of Hearing Loss

Sensorineural - This term describes hearing loss caused by a problem in the inner ear or the nerve that sends signals to the brain.

Conductive - This term describes hearing loss due to a problem with the portion of the middle ear that conducts sound from the outer ear canal to the inner ear. In these cases, the inner ear is not affected.

Mixed - This term describes hearing loss with a sensorineural and conductive component. Mixed hearing loss is caused by a problem with the conduction of sound through the middle ear and an inner ear or nerve loss.

Treatment Options

Depending on the type of hearing loss you have, the audiologist may refer you to see an ENT (ear, nose and throat physician) or Otologist/Neurotologist (an ENT who specializes in ears) as a first step before looking at options for amplification. Since some causes of conductive or mixed losses may be treated medically, it is always recommended for that patient to see a physician first to asses any potential opportunity for medically improving the hearing and then reassessing the need for amplification. There are also specific patterns in a sensorineural loss where it will be necessary for a patient to seek medical clearance prior to purchasing hearing devices.
When medical treatment is not an option for a patient, the next step is looking at amplification- hearing devices. When you decide it is time to learn about your hearing device options, we will schedule you for a hearing device consultation with one of our providers. It is during this appointment where we will show you all the new styles and technologies of hearing devices that fit your particular hearing, lifestyle and budget needs. Hearing device technology has improved dramatically over the years. They are much smaller-less visible, more comfortable, more natural sounding and have much improved technology for understanding speech in noisy environments like a restaurant. For most patients, the best option will be traditional daily or extended wear hearing devices. For some conductive or single sided deafness cases, your audiologist may discuss different options such as the Baha, a CROS hearing aid or the TransEar. For patients with severe to profound hearing loss who do not receive benefit from traditional hearing devices, they may be referred for a cochlear implant evaluation. Please see our full description of hearing device options.

Hearing Evaluation Demo

What Is Hearing Loss?

Hearing Loss Simulator

Hearing Loss | Degrees of Loss


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