March 18, 2014
Do tinnitus treatments work?
Do tinnitus treatments work?
Much has been written, here and elsewhere, about treatments
for tinnitus, the often bothersome perception of phantom sounds. These sounds
are reported as ringing, buzzing, hissing, humming or other essentially steady
sounds in one or both ears. In our experience the problem is not the noise
itself, it’s the patient’s reaction to the noise, or the degree to which he or
she actively listens to the sounds. Tinnitus turns out to be a problem of “hypermonitoring”
Many patients report they rarely pay attention to their
tinnitus. They typically hear it more during quiet times but may not regard the
sounds as worthy of their attention. The brain can “let go of” or ignore
stimulation it does not consider important enough to monitor. This is partly
due to a safety mechanism whereby we monitor our environment for potential
threats. Sounds that are well known to us as non-threatening are not given high
priority. Think of the hum of a refrigerator vs the strident sound of a
rattlesnake. Which sound deserves more attention? In fact, we are more likely
to pay attention to an appliance when it is malfunctioning and producing an
unusual noise. It is interesting that many patients liken their tinnitus to
cricket chirping, yet they do not complain of real crickets during the summer. Also
a lighted candle can be dominant in an otherwise dark room, but seems insignificant
in a well-lit room. This demonstrates how our environment and expectations
influence our perceptions.
At Clear Choice Hearing and Balance our treatments safely
promote the process of habituation, whereby the tinnitus can eventually become
no more threatening than a refrigerator. This process typically takes time when
protocols are applied consistently, but studies have found that it is effective
70-90% of the time when compared to older methods such as “masking”. Other
studies have examined the factors contributing to success of treatment, and the
most important factor was patient follow-through of protocols, particularly
concerning instrumentation when products have been recommended. For example, patients
with significant hearing loss should wear hearing aids, and other devices, such
as the Serenade® device by SoundCure™, have been used in treatment. High
compliance correlated to good success, whereas poor compliance did not.
This process may take the form of a gradual lessening of
awareness at all times, but often the result is shrinking “windows” of time
when the tinnitus is bothersome. Either way thousands of patients across the
world have learned from experience that a true “cure” is not necessary if the
sounds of tinnitus become just another benign part of your auditory world.
Contact us and let us explain further and help put you on a clear path to good hearing and ear
February 26, 2014
Are medications always the answer?
Are medications always necessary?
Lately it seems hard to escape the constant flow of
pharmaceutical commercials and print ads for a seemingly endless list of
maladies. In our own office we see many patients whose medication lists span
more than a full page. All of the drugs listed may be necessary and effective,
however, do ALL disorders require medications, and can drugs (or surgery) cure
or improve all conditions?
In our work diagnosing balance/dizziness disorders, we often
find problems caused by the “vestibular system”, or the inner ear balance
center. The ear is a balance organ first, a hearing organ second. Our VNG
(videonystagmography) test battery provides clues about the origin of the “lesion”.
The eyes, it turns out, are not only the “windows to the soul”, they are the
windows to the inner ear. When eye movements follow a particular pattern, we
may discover one ear is weakened in its ability to send nerve impulses to the
brain when the head changes position. This may be due to conditions such as
labyrinthitis or vestibular neuronitis, and dizziness are the result of
mismatched messages from the ears. Normally the ears work as equal partners,
however, if one is damaged and sending weaker signals, the brain may not be
sure which ear to “listen to”.
Research has shown that medications given to ease symptoms
by suppressing the vestibular system cannot strengthen the weaker ear, but can
actually delay improvement in symptoms. Vestibular rehabilitation therapy can
promote a “recalibration” of the brain to mismatched signal strengths and
improve patients’ symptoms without medications.
A very common vestibular problem is positional vertigo
(BPPV), in which tiny bits of debris (“ear stones”) block one of the
semicircular canals. Again, this disrupts the signals the brain has become
accustomed to for information about the position of the head, resulting in
intense, brief spinning dizziness. When this is discovered, treatment involves
a specific series of movements designed to clear the debris from the canal. It
is not reasonable to assume a drug can seek out calcium crystals and physically
Finally, it has been mentioned here and elsewhere that
tinnitus (phantom noises in the ears) should not be treated with medications.
Drugs such as antidepressants should be taken only for their intended purpose.
For some patients, an underlying psychological condition may exacerbate the reaction
to tinnitus. This should be discussed with a psychologist or psychiatrist,
however, tinnitus on its own does NOT require medicine. Strategies such as
Tinnitus Retraining Therapy and/or amplification can be very effective without
changing your blood chemistry or causing side effects.
Modern-day medications can improve or alleviate many
ailments, however, medications are not always the best option for all
conditions. An otologist or audiologist can help you select the most effective
January 10, 2014
See local professionals who are truly LOCAL
Seek local professionals who are truly local
Much has been made in the press lately about businesses and
jobs leaving or staying in New York State. One can easily argue the pros and
cons of remaining in NY, however, it is no secret we have a long-standing tradition
of excellence in the Rochester area in terms of the medical, engineering,
optical, arts and academic fields. Our region is even an important and vital
place to the Deaf community. We are the original home of Kodak, Xerox, Wegman’s,
Bausch and Lomb, Paychex, Genesee Brewing, Hickey Freeman and many other influential
businesses. Local professors and researchers are consulted regularly by
national news sources. Performers such as Garth Fagan, Chuck Mangione, Renee
Fleming, Cab Callaway and Lou Gramm have called Rochester home. One could
conceivably live an entire day using only products, services, information and
entertainment originating right in our back yard.
There is a trend in the business world to grow outward
and/or expand the scope of one’s reach. Major retailers are now adding grocery
market sections, optical centers, automotive areas and even hearing centers.
People are likely enticed by the convenience of “under one roof” shopping, perceived
low prices and “discounts”. This retail model, as applied to the hearing
center, carries with it several troubling implications. Hearing instruments are
sold as appliances to “customers” instead of being dispensed as medical devices
to patients. True diagnostic examinations may not be performed at all (see
earlier blog entries on free screenings vs. diagnostic testing). The
qualifications and experience of the employees may be limited. Finally, money
paid for products and services will end up primarily at corporate headquarters
instead of being reinvested in the local economy.
Similarly, there are stand-alone hearing centers whose
headquarters exist out of state. Some of these are large, publicly traded
corporations. Their professionals typically do not have the autonomy to select from
an array of product brands or services to which a local business has access. Audiology
and hearing aid dispensing are equal parts science and art. A hearing-impaired
person in search of help should not have to be worried that his needs are
secondary to the needs of stockholders and CFOs. If you call a center, even if
the phone number appears local, ask the person who answers if the call is
received locally AND if the business is wholly owned locally. Often calls are
routed to phone banks at corporate headquarters far from New York State.
There are several excellent locally owned and operated
hearing centers in this region. We hope you choose us, of course, but no matter
who you see, be sure to keep it local. You only get one set of ears!
December 16, 2013
More on screenings vs diagnostic evaluations
Screenings vs diagnostic evaluations
Hearing centers may occasionally produce marketing materials
enticing potential patients or clients with “free hearing screenings”. While
the idea of getting some service for free may be initially appealing, and while
quick screenings can be useful at informal occasions such as health fairs, they
are of extremely limited benefit to people
who have genuine concerns for their hearing or ear health.
The purpose of a screening is to identify a potential problem with hearing or the
health of the ears. The subject is asked to respond to tones presented to one
or both ears until the lowest levels of sound detected by the subject are
recorded. This may be performed in a room that is not isolated from outside
noise. The only information generated in this scenario is difficulty with
certain tones in the specific environment used for the screening. Precise hearing
levels in quiet, word recognition, and “site of lesion” (outer ear, middle ear,
inner ear, auditory nerve pathway, etc.) cannot be evaluated in this manner. A
“failed” screening identifying a potential problem should necessitate a full diagnostic battery.
Diagnostic audiometric evaluations are always the standard
in identifying and quantifying disorders of hearing and their likely origins.
Appropriate treatment depends on accurate, reliable and valid examinations of
the elements of hearing in a sound-shielded environment. In our office we “work
our way inward”. We begin with a fiber-optic high-resolution magnified video image
of the outer ear structures, from the pinna (visible area) through the canal to
the eardrum. Is cerumen (ear wax) interfering with hearing? Then, since we
cannot see past the drum, we use tympanometry
to determine the health of the middle ear space, which includes the three tiny
bones (ossicles) behind the drum and the Eustachian tube, which drains the
middle ear to the throat and allows air to infiltrate the space. Acoustic reflexes rely on the auditory
nerve and facial nerve while protecting us from loud sounds. Otoacoustic emissions use a variation of
SONAR technology to gauge the integrity of cells in the inner ear hearing
organs (specifically “outer hair cells”).
Along with these “objective tests”, the subject must enter a
sound-treated booth and don special headphones or earphones and respond to
tones. Ear-specific threshold levels are obtained for many frequencies,
revealing the subject’s absolute limits of hearing soft sounds. Threshold
levels for words are also measured, after which word recognition percentage is
determined for each ear using approved word lists at a “comfortably loud”
level. Bone conduction tone thresholds should be measured, in order to
determine if a “conductive loss” in the outer or middle ear is preventing sound
energy from reaching the inner ear.
All the diagnostic information can be integrated by an
audiologist to determine if atypical or unexpected results require referrals to
other professionals, such as otolaryngologists. These physicians may order
imaging studies and/or diagnose diseases of the ear that may be treated
medically or surgically. More typical results are evaluated for level of
impairment, in order to inform the audiologist and patient and guide the best
options such as hearing aid use, hearing protection devices, communication
strategies and more. Caring for ears and hearing often takes a team effort. A
five minute screening is not sufficient for effective management of most
November 15, 2013
What is positional vertigo?
Many people use “dizziness” and “vertigo” interchangeably. While the group of conditions known as vertigo produce dizziness sensations, not all dizziness is vertigo. Let us examine the difference in these terms.
Dizziness essentially refers to a sense of physical disorientation in space or illusory movement. There may also be a sense of “light-headedness”, where the person may suffer momentary altered sensations, such as blurred vision and difficulty maintaining balance. One such condition is known as orthostatic (or positional) hypotension, which is temporary low blood pressure in the head. The brain and sense organs of the head are the biggest consumers of the oxygen carried in the bloodstream. When the head rises (as from a bed) too rapidly, the resulting lack of oxygen reaching the head can momentarily cause a dulling of the senses and “dizziness”. This typically lasts for seconds. Similar sensations of unsteadiness can also be psychologically influenced, such as that caused by fear of heights, bridges or enclosed spaces.
Vertigo, on the other hand, typically refers to a spinning sensation and is most often related to the main balance organs of the body, the ears. Benign Paroxysmal Positional Vertigo (BPPV) is a common condition that causes many people to avoid provoking movements, such as bending downward, lying back or rolling in bed. It is caused by an accumulation of mineral debris which has migrated from one part of the inner ear (the saccule) into one of the semicircular canals. These calcium-based otoliths “ear stones” are used to sense linear acceleration, as motion causes them to move toward, and bend, specialized cilia on balance receptors known as “hair cells”. When the acceleration signals from both ears match each other and reinforce what the eyes see, we sense acceleration. If the debris happens to block one of the semicircular canals, which detect “angular acceleration”, the brain will receive mismatched signals about the head’s position or movement. Dizziness is the mind’s way of expression confusion with conflicting information.
Positional vertigo typically is triggered by movement or position. Its most common presentation, posterior canal BPPV, canalithiasis variant, is characterized by spinning dizziness, nausea, a twisting movement of the eyes and brief duration (15-30 seconds). The symptoms typically fatigue upon repetition, and repeated movements tend to result in milder dizziness.
The quickest, least invasive, most cost-effective and best treatment for BPPV is called a canalith repositioning maneuver. With versions named after researchers named Epley, Semont, Gans and others, the clinician uses gravity and the density of the particles to unblock the canals and allow the debris to clear into an area where it can be easily absorbed. Obviously no medication can specifically target crystalline debris in the inner ear, pick up the stones and remove them.
November 8, 2013
Just as our eyes inform us of the position of people or objects in our environment, our ears are also directional. Young children learn to turn their heads towards a sound. Stereo recordings fill our heads with music that stretches from side to side and fills the space in between. It is also not difficult to notice the safety implications of judging the direction of sounds that signal imminent danger. How does this work, and how do we incorporate both ears to identify the direction of a sound source?
Our ears have been placed on the sides of our head and are essentially oriented “forward”. The conical shape of the outer ear “pinna” (the visible portion) favors sounds coming from the front. This is not difficult to understand, given the emphasis on vision in communication. We like to see whomever we’re talking to. Sounds from directly in front of us tend to sound relatively even between the ears. Sounds from the side, however, “sound like” they’re coming from that side.
High-frequency (high-pitched, as whistles and speech sounds such as /s/, /f/, and /th/) sounds are localized by our ears from left-to-right based on the relative level of sound. Known as the “interaural level difference”, sounds that are more intense on one side will be sensed toward the more intense side. Low-frequency (“bass” sounds and vowel sounds in speech), on the other hand, are localized according to “interaural time difference”. The ear receiving the signal first will be assumed to be the side from where the sound originates. In both cases the greater the difference from ear to ear the more lateral the sound will appear. Sounds from the extreme left or right are also easily judged due to the “head shadow”, where the farther ear has sound blocked by the head. Stereo recording exploits another phenomenon called the “Stenger Principle”. If both ears receive the same signal directly, as through headphones, but the sound is more intense on one side, the listener will only perceive the louder side.
Scientists have discovered another, more complex, method of sound localization. We have seen the importance of utilizing both ears for localization, however, researchers have found that the folds and contours of the outer ear not only funnel the sound energy toward the eardrum, they cause reflections of the sound waves that may reinforce or interfere with the original waves. These reflections will differ based on the angle of the incoming sound. This is known as a Head Related Transfer Function (HRTF), which requires only one ear and is reinforced by the experience of the listener. Sounds moving around the head will produce changing reflections of sound, and the brain learns to recognize the difference between various angles. “3D sound” technology has been able to mimic this phenomenon through selected filtering of sound, generating an illusion of three-dimensional space. Sounds are not only localized left-to-right, but also top-to-bottom and front-to-back. See www.youtube.com/watch?v=5oAPsP2JZ9s for an amusing demonstration that requires headphones.
For our daily activities it is readily apparent that localizing sound is important not just for safety, but for effective communication. Hearing impairments interfere with all of the localization methods we’ve discussed, therefore it is imperative to ask your hearing professional how to best preserve and maximize this important and complex aspect of hearing. Let us keep you on a clear path to good hearing and ear health.
October 30, 2013
hearing loss vs deafness
Often we see patients with hearing loss who refer to themselves as “deaf”. Spouses may also chime in, “See, I told you you were deaf”. While we do not downplay the effects of hearing loss, we always gently correct the speaker when it is not used correctly. Mild or moderate hearing impairment and deafness are no more synonymous than near-sightedness and blindness. The distinctions are important and bear an explanation.
In typical audiological use “hearing loss” is just that. It is a reduction of the sense of hearing, regardless of degree, from a previous level. Most people who are hard of hearing are “hearing people” who have (gradually or suddenly) experienced more difficulty using their ears to communicate. This may be due to genetic conditions, ear malformations, disease, medications, noise abuse, trauma, aging or a combination of factors. This can be a devastating condition for patients who have always relied on hearing as their primary mode of communication. These people find themselves relying on strategies such as lip-reading, using captioning and using amplification, in order to maximize whatever hearing they retain. This describes many hearing aid wearers. They are able to hear, but their damaged ears require increased intensity of sound, and they often hear very well with amplification. Often certain sounds can be heard reasonably well (typically low frequency “bass” sounds) while higher-pitched sounds are impaired. Unfortunately English and many other languages emphasize high-frequency sounds for clarity.
On occasions where there is essentially a total lack of hearing (over 90 decibels is required for the person to detect a sound), we use the term “deaf”. At this level of hearing impairment one cannot generally use sound as a primary mode of communication, given the acoustic complexity of spoken language, particularly if the condition is longstanding. Many people are born deaf and have never actually “lost” hearing. Communication via a signed visual language, such as American Sign Language (ASL), Signed Exact English or finger spelling, becomes a primary method with an added benefit that it is mutually accessible to hearing people. Deaf people also utilize facial expressions and other non-verbal cues to add emphasis to a greater degree than hearing people. These methods work perfectly well along with written language and visual alerts, and deaf people may arguably be considered less “handicapped” than hearing-impaired people who have lost the sounds they relied on so heavily.
When a deaf person wishes to hear (many prefer to maintain their deafness), often even the most powerful hearing aids are inadequate for listening effectively to speech. Many deaf people wear hearing aids primarily to hear environmental sounds or elements of music. Often patients who have been deafened after learning language will use a cochlear implant (CI). This device converts acoustic signals into electrical impulses that stimulate the auditory nerve directly. The nerve fibers project to the same auditory brain region as in hearing people. While many report the sound can be “mechanical” or “metallic” and harsh at first, auditory memory and experience enable many patients to hear at near-normal levels.
October 14, 2013
hearing health risk factors
Risk factors for hearing loss
A thorough audiological examination should begin with a careful medical history. Along with the actual presenting complaint or symptoms, listening to past history is an important early step in helping determine the source of the patient’s problem. Risk factors are any and all pieces of information about a patient’s history that suggest increased likelihood of a problem. Obviously, conditions such as a hernia or sprained ankle are not likely to be related to hearing. There are, however, many conditions, diseases or lifestyle choices that can affect the ears. These should be known to the examiner if we wish to understand the patient’s condition fully.
Let us examine some risk factors for hearing.
- Family history. Having relatives with ear conditions (not otherwise explained by environmental factors, such as lifestyle or occupation) increases the likelihood of problems. Genetic factors may be at work.
- Noise exposure. OSHA workplace regulations limit allowable noise exposure times beginning at 85 decibels. Sound intensity and duration of exposure interact to produce safe or unsafe “doses” of exposure. The mechanism of noise damage will be the topic of a future article, however, the public needs to be aware that activities such as lawn mowing, live music, extensive headphone use, power tool use, firearms use, factory work and even attendance at events with massive live audiences (such as NFL games) can produce inner ear damage.
- Toxicity. Many medications, such as certain classes of antibiotics (particularly aminoglycosides), chemotherapy agents, diuretics, quinine, analgesics and even erectile dysfunction drugs can be harmful to the ears. Environmental substances, such as toluene, may also be toxic to hearing and/or balance function.
- Illness. Diseases such as diabetes, meningitis, vascular conditions, otosclerosis, Eustachian tube dysfunction, Meniere’s disease, labyrinthitis, autoimmune conditions and many others are associated with increased risk for hearing loss.
Often the above risk factors can interact. For example a noise exposed person with a family history of hearing loss working with toxic chemicals is certainly at higher risk when all these factors are taken into consideration. Any individual who suspects multiple risk factors needs to exercise even greater vigilance in protecting and monitoring his or her hearing. This should include periodic audiometric evaluations.
September 6, 2013
Is it hearing or "processing"?
Many patients enter the test booth of an audiology center convinced of a decrease in their ability to hear. The most common reason given is difficulty following conversation, perhaps most markedly in subpar acoustic environments. Often spouses or family members make note of changes over time. They may even report an increase in TV volume. What are we to decide when the hearing evaluation reveals normal middle ear function and no change in actual hearing levels?
Research on the brain and hearing system has demonstrated the possibility of disruptions in listening capability NOT directly related to hearing levels. We have stated in earlier blog entries the complexity of the hearing system, from the outer ear to the cortex of the brain. This system depends on the "transduction" of acoustic sound energy to mechanical vibrations to nerve impulse patterns involving multiple structures and a pathway routing information, often in both directions. Any malfunction or interruption of the speed of transmission of all this information may interfere with what we call AUDITORY PROCESSING.
Auditory processing refers to the coordination within the hearing system that accurately transports auditory signals towards the brain and extracts meaning from the information. Processing disorders can interfere with timing of the signals reaching the brain, the ability to utilize both ears effectively, the ability to understand a message with missing information (such as in poor acoustic environments), and other necessary elements of good hearing.
Strategies of habilitation for impaired auditory processing may differ from those found to be effective for common hearing loss. Identification is the first step. Let us evaluate your ears and determine the best path to take to maximize hearing, communication and quality of life.
August 5, 2013
The problem with ears...
The problem with ears
Often patients, especially new patients, will remark on the extensive testing we perform and the equipment we use. Often they have never seen or experienced such an array of diagnostics examining various parts of the ear and hearing system. “For my commercial driver’s license test they just stood behind me and whispered”. “When they tested me at ____ (retail hearing aid center), we were in a room with other people and copying machines running. All I had to do was click the clicker when I heard a sound, but you’re doing so much more”, etc. Many patients seem impressed at our comprehensive test battery, but we like to explain the value of each test. They do not exist merely to give the appearance of thoroughness; we are gathering information and making judgments about a very elusive system that can’t be directly observed.
Most of us learned in school that the ear has “three parts, the outer, middle, and inner ear” without a good understanding of where one region ends and another begins. Many people will complain of pain in the “inner ear” any time the sensation is deep and away from the pinna (the visible portion of the outer ear). In our office we use a high-resolution fiber optic camera to visualize the ear canal, and the patient can look as well. Barring wax or other occlusion or malformation, the tympanic membrane (eardrum) is as far as we can see even with a camera or microscope. Often the middle ear bones, or ossicles, can be seen behind some eardrums. The region that can be seen through the canal is just the beginning of the hearing mechanism.
The true “inner ear”, also known as the cochlea, lies past the ossicles and is encased in part of the temporal bone of the skull. Neither the oval window nor the round window provides even a reasonable view of the workings of the inner ear (perhaps they were poorly named!). The organs of hearing, where mechanical energy is converted to electrochemical nerve impulses that travel towards the brain, are housed in complex structures within the cochlea. Even advanced MRI, CT, PET or ultrasound imaging can inform the clinician if the inner ear is functioning normally, as the structures are neither bone, nerve or vascular in nature.
We have described the tests we use to locate damage in the outer, middle and inner ears in previous blog entries. We use them because visual inspection of the ear canal and the patients’ symptoms are simply not sufficient for a diagnosis. Often the eye can be fooled. Patients with apparent eardrum perforations, as viewed through an otoscope or microscope, often prove to have a perfectly sound drum, as verified by tympanometry, an objective measurement that relies on reflected sound and measurement of ear canal volume.
Always opt for a full diagnostic evaluation when your ears are in question. Let us put you on a clear path to good hearing and ear health.
July 23, 2013
A patient came to our office with complaints of uneven hearing, balance difficulty and tinnitus in the poorer hearing ear. This condition did not happen overnight, but had worsened over time. The woman was fearful she would lose hearing in the other ear and not regain her balance functions.
Audiologists are trained in the recognition of “red flags”, or telltale signs of conditions requiring further medical investigation. The patient’s history often speaks volumes about potential diagnoses, therefore, we ask very specific questions regarding risk factors, other medical conditions and new or changing symptoms. Diagnostically, we seek symmetry in the clinical signs from right ear to left. The majority of hearing loss cases affect both ears to a similar degree. A “bad ear” and a “good ear” raise immediate suspicion. Add difficulty with balance, vertigo, atypically poor word recognition, gait disturbance, headache, pressure sensations and one-sided ear ringing, and we begin to suspect the possibility of “retrocochlear disease”, which refers to pathology along the nerve pathway connecting the inner ear to the brain.
A common retrocochlear disorder is an acoustic neuroma. It is often said that “vestibular schwannoma” is a more accurate term, as the tumor arises from Schwann cells instead of neurons themselves, and the vestibular portion of the auditory nerve is more commonly affected. The canal through which the nerve travels through the temporal bone towards the brainstem is the site of lesion. The area known as the “cerebello-pontine angle” is often implicated. This growth is generally benign (non-cancerous) and slow growing. Since the presence of this neoplasm disrupts the synchrony of firing of individual nerve fibers along the nerve, one test that can aid in diagnosis is an ABR (acoustic brainstem response), a type of EEG, although most otolaryngologists prefer an MRI imaging study of the cerebello-pontine region.
Treatment is generally surgical, and is a decision made between otologist and patient. Hearing may be spared, although not necessarily improved, by surgical management. The otologist may choose to observe the tumor and symptoms over time before proceeding with treatment. The patient will often be left with a significant hearing asymmetry. This can generally be habilitated with a hearing aid if residual hearing is sufficient to derive benefit from amplification. Thorough diagnostics, including intensive word recognition testing, will help determine the potential benefit of hearing aids. The first step, as always, is a thorough diagnostic workup and a discussion of all appropriate options.
June 14, 2013
"Current" thoughts on the hearing system - inner ear to the brain
Beyond the middle ear; “current” thoughts about hearing, the inner ear, the nervous system and the brain. Part two in a series of blogs about the physiology of hearing.
In our previous blog entry we discussed the transmission of sound energy from vibrations of air molecules to mechanical vibrations carrying the properties of sound in the middle ear. Eventually, in order for the brain to listen to sounds, this energy must be transformed into the electrochemical signals the nervous system utilizes to gather information.
As the footplate of the stapes bone (the “stirrup”) vibrates at the oval window of the cochlea, or inner ear, all the amplified vibrations from every sound we hear at all times cause the fluid inside to vibrate as a travelling wave. Smack the surface of swimming pool water with your palm and you will cause waves. Now imagine waves travelling from one end of the inner ear to the other, often thousands of times per second. These waves cause the “basilar membrane” to rise and fall, similar to a buoy on the water’s surface.
Spaced along the basilar membrane, which separates two fluid-filled chambers, are several thousand “organs of Corti”, which are the true organs of hearing. “Inner hair cells” with whip-like cilia at the end jostle in the fluid in which they are bathed every time the membrane vibrates. If the vibration is sufficiently strong, the cilia will bend and trigger a nerve impulse towards the brain. “Outer hair cells” are not receptors, but they help ensure only the organs at the peak of each vibration (closer to the oval window for high-pitched sounds and farther for lows) transmit a signal to carry the frequency of the sound. They also act as an amplifier and are responsible for hearing soft sounds. The nerve pathway beginning at every point along the basilar membrane carries the signal to a specific brain region responsible for interpreting that frequency (which we interpret as the “pitch” of the sound).
These nerve “spikes” carried by individual neurons (which gather into a bundle known as the auditory nerve) travel in synchrony toward the temporal lobe of the brain. Other regions of the brainstem, midbrain and thalamus help us organize and analyze the information into coherent sounds before it reaches the cortex, the outer “smart” part of the brain, specifically in the temporal lobe.
It is interesting to note the brain does not “hear” any sound vibrations at all. It only receives messages coded in the patterns of nerve impulses and the specific brain regions that are stimulated. The brain can use this information to analyze, recognize, process and remember sounds, thereby extracting all available information carried by the neuron firing patterns.
To summarize, hearing is a complex chain of events involving transformation of sound vibrations to mechanical vibrations to fluid wave motion to electrochemical nerve transmission to complex interpretation in the brain. Any miscue in this process can cause problems hearing or interpreting sounds. Therefore, it is imperative to protect the system we have. As always we will help keep you on a “clear path” to good hearing.
May 31, 2013
There's more to hearing than meets the eye!
It is commonly accepted that we hear the world with our ears. Early man must have noticed that when the ear canals are blocked, hearing decreases. Everyone can observe the outer ear and a canal that travels into the head, but what is really happening when we hear a sound, say, a person talking, music playing or a warning alert? There’s probably more going on than meets the eye, you’re guessing, and you are correct.
This article will be the first of a two part series dealing with the complexity of hearing and our body’s hearing system. Here we will deal with the outer and middle ears. Part two will examine the inner ear and brain structures.
Our outer ears have their peculiar shape for a good reason. As sound waves propagate through the air, our funnel-shaped ears can pull in more sound than two small holes on the sides of our heads. They also face forward, as it is most likely we seek to emphasize what we can see in front of us.
When the sound waves travel inward, they cause the tympanic membrane (eardrum) to vibrate. This three-layer membrane of modified skin tissue “transduces” sound energy into mechanical vibrations. Every sound we can detect has the property of “frequency”, or the number of vibrations per second. A high-frequency sound is high-pitched; think of a violin compared to a bass drum. Our eardrum is such a sensitive instrument, it can and does vibrate at the same frequency as every sound we receive ALL the time. The drum also signals the intensity of the sound, by vibrating with more force in response to louder sounds.
Attached to the back of the eardrum is a chain of three tiny bones, the ossicles. These bones vibrate with the eardrum and transmit the vibrations inward with even greater force. The third bone, the stapes (“stirrup”) is connected to the inner ear (the cochlea) by a ligament at the “oval window”. Vibrations into the oval window become fluid waves in the inner ear, as we will see in our next article. The middle ear space occupied by the ossicles is typically empty and air-filled. It connects to the throat via the Eustachian tube, which allows us to “pop” our ears when pressure changes, and allow air into the middle ear and fluid OUT of the ear.
Problems with the outer or middle ears can produce a “conductive hearing loss”, or a disruption in the conduction of sound energy toward the inner ear. Often such losses can be treated medically or surgically, restoring some or all of the original hearing.
In our next blog entry we will explore the inner ear and the auditory pathways leading to the brain.
May 17, 2013
Elements of diagnosis: word testing
The importance of word testing.
There is a conventional battery of tests, with a few variations, that give an audiologist diagnostic information about a patient’s ear health and hearing capabilities. Otoscopy allows the examiner to visualize the outer ear, including the external ear canal all the way to the tympanic membrane (eardrum) for malformations, blockages or signs of trauma or disease. Pure tone audiometry assesses the intensity level necessary for a patient to barely detect various frequencies of sound within the spectrum of human hearing. Bone conduction determines the degree to which the outer and middle ear may reduce the amount of sound energy that reaches the inner ear by quantifying any “conductive loss”. Tympanometry, acoustic reflexes and otoacoustic emissions are objective tests of ear function (not hearing per se), and have been described in earlier blog entries. Another vital area of diagnosis is word testing.
There are several reasons audiologists test with words native to the test subject. Verbal communication is obviously the most important reason we have a hearing system, along with safety. Helen Keller famously observed that loss of vision “separates us from objects”, but hearing loss “separates us from people”. This is truer of people who have lost hearing than of people born deaf, but the fact remains that verbal communication is of immeasurable importance for most of us and is the deficit hearing impaired patients complain most bitterly about.
A second reason word testing is necessary is that certain patterns of errors that can ONLY be revealed by careful test administration can act as “red flags” for conditions that require referrals to other specialists, such as otolaryngologists, and additional testing, such as MRI. A competent tester must be familiar with these signs and the proper procedures.
Thirdly, for the many patients who require amplification, a good hearing aid dispenser must understand not only the diagnostic implications of word testing, but also be able use the data to guide selection of the most appropriate instruments. Patterns of word errors are typically consistent with patterns of hearing loss and the frequencies of the sounds patients are missing. Often these are high-frequency consonant sounds, such as /s/, /f/ or /th/. Patients must be given expectations for improvement that are high yet realistic. Word testing is a large component of these expectations.
All hearing testing, especially word testing, must be done in a sound-shielded booth through headphones. An approved word list should be used. Words are not randomly chosen, and the intensity level of the presented words must be appropriate. An old-fashioned “whisper test”, where an examiner stands behind the subject and whispers words to be repeated, is virtually useless.
Always be sure to choose a hearing center that tests thoroughly and explains all results and their implications for you as a patient.
May 3, 2013
Information on tinnitus
- Tinnitus is defined as “phantom noise perception” – a real perception of sound that did not originate outside your body.
- Tinnitus was regarded by the ancient Egyptians as private messages directly from the gods! The ancient Greeks recognized tinnitus, but did not have such a positive attitude toward it. They thought you could “chase it away” with sound.
- Tinnitus is perceived by at least 50,000,000 Americans alone. One third of citizens over 65 hear persistent buzzing, ringing, humming or other noises. In a completely soundproof room almost everybody will hear tinnitus.
- To date, no medications or supplements have been found to reduce or eliminate tinnitus without significant side effects, including dependency. Drugs are not recommended and not necessary. Our tinnitus therapy has no side effects.
- Tinnitus very RARELY signals a pathological medical condition.
- Tinnitus is a symptom and not a disease, and it is typically the result of increased nerve activity triggered by damage along the pathways of hearing, often very minor damage.
- Tinnitus is only a problem to the extent that it bothers you.
- Bothersome tinnitus is not a problem of noise perception, but of hypermonitoring the noise.
- Tinnitus does not cause hearing loss, nor does it mask hearing, although it may compete for your attention.
- A majority of tinnitus patients have measurable hearing loss, although not all require hearing aids.
- Habituation, the process that allows us to ignore unpleasant odors or the feeling of our clothes on our skin over time, has been found to be VERY successful with tinnitus patients, if basic protocols of Tinnitus Retraining Therapy (TRT) are followed. Ear-worn sound generating devices, including the Serenade® device by SoundCure™, have been found to significantly increase the habituation process in many patients.
- Patients often compare their tinnitus to crickets or “white noise”, yet people rarely tend to be bothered by real crickets or white noise. It’s the significance attached to the sound, and not the sound itself, that is an annoyance. It is a learned behavior we can “unlearn”!