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What's the difference between an audiologist and a hearing instrument specialist? - Ted Venema PhD
More than three million (3,000,000) Canadians suffer some degree of hearing loss, and yet, hearing loss and it’s effects on the lives of those affected, remains one of the least understood and most frequently undiagnosed human tragedies of our time.
Hearing loss is often referred to as “the unseen handicap”. Because of its slow insidious progress, the hearing impaired person adapts to his condition as his hearing deteriorates. He begins to believe that not understanding speech in the presence of noise, in groups of people, and when someone speaks quickly, is normal. As the hearing loss continues undiagnosed, the difficulty of not understanding speech clearly can progressively become a permanent condition.
Hearing loss has many faces. Many elderly persons with undiagnosed hearing loss are seen as uncommunicative, self-isolating, unco-operative and, in extreme cases, mentally incapacitated.
The Canadian Hearing Instrument Practitioners Society (C.H.I.P.S.) has created this website and a booklet for consumers who may suspect hearing loss, and are unsure of where to look for answers. We believe these guides will answer most of your questions, from what is hearing loss and where to get help, to the type and variety of help that is available. You will also find a section specific to most provinces with information about any regulations or financial assistance that may be beneficial to you.
To most people, hearing loss is invisible. Unlike blindness, there is no white cane for others to see. As a society, we tend to only believe in what we can see. Hearing loss, therefore, often remains hidden from public view. Compared to vision problems and eyeglasses, the subjects of hearing loss and hearing aids have a low profile. Hearing, unlike vision, is our main communicative sense. We mistake hearing loss for lots of things: lack of interest, purposely not listening, and not understanding. For these reasons, hearing is a sense that people tend to sweep under the rug and take for granted. Hearing loss often creeps up in a subtle way, and slowly begins to interfere with our ability to hear common sounds and understand speech. Because this happens so gradually, many are reluctant to go see a Hearing Health Care Professional who can help, not realizing the benefits available to them.
Up to 10% of Canadians have hearing loss - about as many people as in the city of Toronto! Hearing loss is most prevalent in people over 65 years of age, but many children and younger adults also live with hearing loss. For many people, the biggest (and most preventable) threat to hearing in our society is noise. We live in an amazinglynoisy society. Industrial machines, and even home power tools can cause hearing loss if the ears are not protected. Loud music is another common source of noise. If you can easily hear sounds coming from someone else’s headphones, chances are very high that the sound level is excessive enough to threaten the safety of that person’s hearing.
There are three main parts of the ear - the outer, middle, and inner ear. The outer ear is the largest and yet, the least useful part for hearing. It mainly serves to gather sound and funnel it down the ear canal to the eardrum. Like blowing across a partially filled pop bottle, the ear canal resonates (vibrates) more with some sounds than with others. The amazing thing here is that it resonates especially well with the sounds that are most important for hearing speech (high pitch or frequency.)
The middle ear is behind the eardrum, and it is a small air-filled room that houses the three smallest bones in the body (the “hammer”, “anvil” and “stirrup”.) The vibrations of sound against the eardrum vibrate these tiny bones. The whole purpose of the middle ear is to convert the sound waves (air pressure) to mechanical energy, amplifying sound as it carries it to the fluid-filled inner ear. As we all know, if our heads are under water in a pool, our ears won’t pick up much sound from someone talking at the side of the pool, outside of the water. This is the same effect as when the ear is plugged with cerumen (wax). Something has to increase the intensity of the sound so it will penetrate the fluid and be heard clearly by the ear. That something is the middle ear. Sounds hitting the relatively large eardrum are transmitted to the tiniest, third middle ear bone, called the stapes (nicknamed the stirrup because it looks like a tiny stirrup). If you want an example of this, press your hand against the side of your face with a certain amount of force; now, with the same amount of force, press only a finger tip against your face. Feel the difference in pressure? The middle ear basically makes incoming sound intensity greater (approximately seventeen times greater), so that it can penetrate the fluid-filled inner ear.
The inner ear is a very exciting place. It is called the “cochlea,” (Greek for snail shell.) The fluid-filled cochlea in a human being is about the size of the tip of your little finger, and is embedded inside the hardest and most dense bone in your skull. There are about 15,000 tiny “hair cells” that are completely surrounded by the fluid inside each cochlea. The hairs on these cells are not like hairs on our head but they do look a bit like tiny hairs. The vibrating middle ear bones create ripples in the cochlear fluid. This in turn, causes the tiny hairs to bend, which creates tiny electrical currents that are sent on to the brain. In one sentence, the cochlea changes sound vibrations into electricity, and electricity is the “language” that the brain understands.
Now that we’ve reviewed how the ear works, we can discuss what can go wrong with your hearing. This will help clarify what hearing aids can do for those with hearing loss. In the world of vision, most of the public is quite aware of “nearsightedness” and “farsightedness.” Yet most of us have never heard of the two main types of hearing loss: “conductive” and “sensorineural.”
Problems with the outer or middle ear cause conductive hearing loss. These problems tend to reduce the passage of sound as it moves (or is conducted) towards the inner ear. As examples, think of excessive earwax or middle ear infections. Conductive hearing loss can often be repaired by today’s medical intervention (ie: wax removal, antibiotics or surgery.) When medical intervention is not recommended, hearing aids usually perform quite well to overcome a conductive hearing loss.
Sensorineural hearing loss is caused by problems with the inner ear, or cochlea. This is by far the most common type of hearing loss. It is caused by damage to the tiny hair cells inside the cochlea. The damaged hair cells can no longer change sound into electricity as well as they could before, and as a result, hearing loss occurs. Hair cell damage can affect high, mid, or low pitches of hearing. Sometimes it affects all the pitches of one’s hearing, but usually not all to the same degree. Sensorineural hearing loss is rarely improved with medical intervention. What is gone is gone, and generally cannot be restored. (In some scientific studies, hair cells are being regenerated in mice and in birds, but we are not yet near the stage of restoring new hair cells in mammals or humans.)
One type of sensorineural hearing loss that occurs as a natural process of aging is called “presbycusis.” Presbycusis occurs in both ears (because both ears age the same amount) and it usually affects the treble, or higher, pitches first. As mentioned earlier, a reduced ability to hear the sharp, high-pitched consonants of speech prompts elderly people to sometimes say that “young people mumble a lot these days.”
Noise-induced hearing loss (NIHL) is another type of sensorineural hearing loss that affects mostly the high pitches of hearing. Sensorineural hearing loss is sometimes a genetic trait inherited by a child. It can be caused in a not-yet born infant when the mother has rubella. Sometimes it is caused by excessively high fevers associated with the mumps, etc.
Another cause of sensorineural hearing loss is Meniere’s disease, a condition that produces too much fluid inside of the cochlea.
Ringing in the ears (tinnitus) is occasionally, but not always, associated with sensorineural hearing loss. There are some people with normal, or better than average, hearing who also experience tinnitus.
The degree of hearing loss a person has is expressed in decibels (dB). The greater the damage to a person’s hearing, the larger the number of decibels of hearing loss. While typical conversational speech occurs between 45-55 dB, some components of speech are spoken more softly than others. For example the “s”, “th” “f”, “z” sounds are more softly spoken than lower frequency consonant sounds such as “m” or “n”. Usually, people with hearing loss have more loss in the high frequencies. This is particularly debilitating to understanding speech because we are combining hearing loss with softly spoken speech components. The end result is that people miss what is being said to them and they obtain a hearing aid to help resolve the problem.
Hearing aids can definitely help those with hearing loss. There are, however, many popular misconceptions about hearing aids.
Some people think that “a hearing aid is a hearing aid,” and that “smaller is always better.” Not so! Hearing losses are all different, in degree and in quality. We cannot benefit from our neighbours’ hearing aids any more than we can from their glasses. While hearing aids are designed to fit a range of hearing losses, they are intended to fine-tuned for individual hearing losses.
Many people with hearing loss say that others mumble and do not speak clearly. While this is certainly true in some cases; most people with hearing loss experience increased difficulty hearing the high-pitched, treble sounds that are important for making speech clear. In speech, vowels are relatively lowpitched sounds, and compared to consonants, are few in number. Of the thousands of our words available to use, all have to share these few vowel – every word has at least one. Consonants (like /s/, /f/ and /th/), however, tell the listener what the words are (eg. sat, fat, that). Think of the /s/ and /ch/ in the word “speech.” Compared to the /ee/ sound, these consonant sounds of speech are high in pitch and not as powerful. Without these highpitched consonants, speech sounds quite mumbled or muffled.
Add background noise to a hearing loss that naturally hears deep, strong vowels easier and it becomes especially difficult to distinguish words. Thankfully, today’s hearing aid technology offers several unique ways to deal with the problem of background noise. Hearing aids will be discussed in more detail later on in this guide.
Some people assert that hearing aids cost much more than eyeglasses, and yet they do not work as well. True, they do cost more, but think about what a well-fit hearing aid can offer - improved communication. Quality of life is dramatically enhanced when one is not constantly guessing what others might be saying. As to how well they work, always remember that hearing aids are not new ears. If you know their possibilities and limitations, you will have much more realistic expectations of hearing aids and much greater success with them. It is extremely important to make sure that hearing aid usage and benefits are carefully and clearly explained to you.
Lets finish here by comparing glasses for eyes to hearing aids for ears. In vision, the retina changes light into electricity, just as the cochlea changes sound into electricity. Most people with vision problems do not have damaged retinas; instead, their eyeball is longer or shorter than normal. As a consequence, light coming into the eye is not focused properly on the retina. Lenses refocus this light on the retina. Most vision problems are like having a conductive hearing loss, where nothing is wrong with the cochlea but sound simply has trouble reaching it. Most hearing problems, however, are sensorineural, and this is like vision loss from damage directly to the retina of the eye. Amplified sound from a hearing aid may have no trouble reaching the inner ear or cochlea, but the cochlea itself is damaged. Hearing aids do indeed go a long way towards making previously unheard sound audible once more. One main challenge remains for the person with sensorineural hearing loss who wears hearing aids: separating speech from background noise.
The good news for sensorineural hearing loss is that today’s hearing aids are dealing with exactly this problem. The technology is rapidly and dramatically making in-roads into the problem of background noise. Today’s hearing aids can also deliver specific pitches of sound to someone with specific pitches of hearing loss. In other words, hearing aids can sculpt and shape incoming sound to fit almost any particular hearing loss. This is why no two hearing aids are exactly alike. And once a person’s weakest hearing pitches are addressed by the hearing aid, not only is sound loud enough to hear, but it also becomes more clear.
You may want to have your hearing checked if any of the following apply:
Hearing aids are a unique commodity. They are custom made and custom set to best suit your hearing loss. For this and other good reasons, you cannot simply purchase a hearing aid over the counter. You may have read in magazines about “mail order” devices that look like a hearing aid. If there was a case for “don’t believe everything you read” or “if it sounds too good to be true, then it probably is”, this would be one of them; be cautious of such advertisements.
For many people, this process begins with a visit to their family physician. You may want your doctor to check your ear canals for a buildup of cerumen (ear wax), especially if you’ve ever had them cleaned before, or you suspect this may be at least part of your problem. Since your doctor knows your medical history, they may want to refer you directly to an Otolaryngologist (Ear, Nose and Throat specialist, or E.N.T.). While this doesn’t happen for most people (about 10% benefit from medical intervention for their hearing loss), your doctor can rule out a possible need for medical treatment such as an ear infection or a perforation (hole) in the ear drum. Once your doctor has ruled out any obvious problems, you should then have your hearing tested by a hearing healthcare professional. Your doctor may or may not recommend one in particular. You can also ask someone you know or look in your phone book to find out which professionals work in your area.
Many people also begin this process by having their hearing tested by a Hearing Health Care Professional. If this professional finds any medical red-flags, they will send you to your doctor for review and may suggest referral to an Ear, Nose and Throat Specialist (also known as an ENT or Otolaryngologist). You want to establish a comfortable rapport with the professional who will do your hearing test; this is a relationship that will, for most people, continue for a number of years. The Hearing Health Care Professional is usually an Audiologist or a Hearing Instrument Specialist (sometimes referred to as a Hearing Instrument Practitioner). These trained professionals will evaluate whether you have any hearing loss and whether that loss is significant enough to warrant hearing aid(s). They will also evaluate, and may discuss with you, whether any other types of assistive listening devices will benefit you, either as a complement to the hearing aid(s) or as an interim solution until your hearing loss is significant enough to warrant hearing aids. Most Hearing Health Care Professionals work with an associate(s) on their staff who may continue with or assist with your client care. No matter which type of Hearing Health Care Professional you choose, you should ask about the qualifications of the individual( s) you will be trusting with your hearing health care.
Medical treatment for hearing impairment is generally provided by either a family physician or an Otolaryngologist (ear, nose and throat specialist). The Otolaryngologist specializes in diseases of the ear and they also provide medical and surgical treatment.
Audiologists are university graduates who have also completed a clinical practicum and are members of the Canadian Association of Speech Language Pathologists & Audiologists (CASLPA). Most provinces also have legislation that governs the ethics and actions of practicing Audiologists. Audiologists perform the hearing test and prescribe an appropriate hearing aid(s) for your hearing loss, if present. The Audiologist may also dispense the hearing aid(s) or have one of their staff continue with the fitting of the prescribed hearing aid(s).
Hearing Instrument Specialists’ training includes an internationally recognized course of study through the International Hearing Society (IHS), standardized competency exam through the National Board for Certification in Hearing Instrument Sciences (NBC-HIS) and/or degree programs for Hearing Instrument Specialists (see resource list at end of this guide.)
Some provincial regulations or member organizations require a clinical practicum. Hearing Instrument Specialists perform the hearing test and recommend an appropriate hearing aid(s) for your hearing loss, if present. The Hearing Instrument Specialist may also dispense the hearing aid(s) or have one of their staff continue with the fitting of the recommended hearing aid(s). Each province has specific guidelines for practicing in the hearing health care field. There are provincial associations with whom you can verify the qualifications of the professional you choose. As appropriate, the Hearing Instrument Specialist should be in good standing as a member of their provincial professional association. Please refer to the listing of professional organizations at the end of this guide.
Before performing the hearing test, the professional will obtain a thorough case history. It is important that he or she understand why you are seeking a hearing aid and which listening situations are difficult to you. Your family members will be invited to participate in this discussion, as they are aware of times they have trouble communicating with you. In addition to an assessment of the hearing problem, the dispenser will assess any potential problems requiring medical referral such as active drainage in the ear, sudden or rapidly progressing hearing loss, pain, dizziness or hearing loss on one side only.
The hearing test is comprised of several components, each designed to help the professional better understand the extent of your hearing loss and to help select an appropriate hearing aid to meet that loss. Once the dispenser has looked in your ears to determine that they are free of wax, they will begin the testing process. The initial test procedure is that of pure tone air conduction testing. During this part of the test procedure, headphones or insert earphones (which look like earplugs) are placed on or in your ears and you will be asked to respond each time you hear a tone by raising your hand or pushing a button. A variety of frequencies or pitches will be presented and for each pitch it will be determined how loud the sound must be for it to be just audible for you. Typically, speech testing is performed next. The first measurement, the speech reception threshold (SRT) is obtained using two syllable words such as hotdog or airplane. The intensity of the words are raised or lowered until you are able to understand 50% of the words presented to you. This level helps to show the softest level you can understand speech. Next, the speech discrimination test is performed. This test is done at a constant level and you are asked to repeat single syllable words. This helps to assess your discrimination ability or your ability to understand speech at comfortable levels. Often, following these two tests the dispenser will obtain the intensity of your most comfortable listening level (where speech is most comfortable) as well as your loudness discomfort level (where speech becomes bothersome). These tests are important because the goal of a hearing aid is to amplify sounds to your comfortable listening levels but to not exceed your loudness discomfort level. Sometimes a measurement of loudness discomfort is made using tones rather than words.
Following speech testing, the headset is often switched for a smaller headset which is placed behind your ear and a bone conduction test is performed. Once again, you will be asked to respond to pure tones only this time your outer and middle ear will be bypassed and sound will be delivered via vibration directly to your inner ear. This allows us to verify whether there is a problem in the outer or middle ear requiring medical attention.
The information from the hearing assessment is placed on a graph called the audiogram. The audiogram charts frequencies in Hertz with low pitches or frequencies on the left side of the chart and higher frequencies on the right side of the chart. Soft sounds, measured in decibels (dB) are at the top of the chart and loud sounds are at the bottom of the chart. A person with normal hearing would have thresholds marked on the audiogram for all frequencies between 1 and 25 dB. However, most individuals who obtain their first hearing aid will have fairly normal results in the low frequencies (meaning they hear well in the bass area of sound), but tend to have their thresholds drop off or become poorer in the treble or high frequency areas. This “ski-slope” pattern is typically associated with presbycusis (age related hearing loss.)
While this description is for a typical hearing aid evaluation, each clinic has slightly different procedures so be sure to ask for clarification regarding each portion of the testing procedure and for an explanation of each test result. It is a good idea to obtain a copy of your audiogram and keep it with your health records so you can track any changes in your hearing over time.
Following the assessment, the dispenser will review the test results and outline treatment options with you (and your family – if present.) During this portion of the evaluation, it is helpful to discuss any prior experience with hearing aids and what you expect the hearing aid to do for you. A realistic assessment of what a hearing aid can and cannot do will be offered. While modern hearing aids offer many wonderful advantages over hearing aids of days gone by, they still have some limitations and these will be discussed to help ensure that you are not disappointed with the functioning of your hearing aids once you begin wearing them.
Following this discussion, an ear impression will be taken by injecting your ear canal(s) with a soft silicone material. This material is soft when placed in the ear canal, but hardens in 5-10 minutes and can then be removed. This mold is sent to the hearing aid manufacturer so that a hearing aid or permanent ear mold can be made from it - to match the size and shape of your ear canal. Be certain you understand which style and type of hearing aid has been recommended. Most people have at least a couple different size and style options that will work for them, at different prices. What are its main benefits? How will it address your hearing loss? What will the hearing aid not do for you? Can you see (and personally handle) a sample? Is the hearing aid a comfortable size and style for you to handle? Can you operate all the controls? Does the technology chosen allow for social situations where competing noise makes hearing particularly difficult for you?
Be sure you know the following: