Tips from our Friend and Patient, DR. RANDY BISHOP
Posted August 08, 2020.
Audiology is the study of normal and disordered hearing. It involves both a scientific discipline and a clinical profession. An audiologist is a health care professional that is educated in both of these areas. The entry level degree is a doctorate. The audiologist is credentialed through a professional accrediting body usually after a one year residency and then licensed in their state of residency. This then opens the door to assess hearing and vestibular disorders and manage the hearing impairment. A diagnostic hearing test is not just utilized to identify hearing loss that could be remediated with the use of amplification but first of all and most importantly it’s used torule out other pathologies, some of which are life threatening. This is best determined by a doctor of audiology.
The hearing assessment involves a detailed hearing history as hearing deficits can becaused from different parts of the auditory system. For example: wax or blockage of the outer ear; inflammation or damage in the middle ear or eardrum portion of the hearing system; or hearing loss be caused from noise damage or diseases of the inner ear; trauma or diseases of the brainstem or pathologies of the auditory cortex, which is the primary auditory association area. The history will often point to one of these areas as the site of the hearing disorder.
After assessing the integrity of the ear canal and eardrum by using a tool called an otoscope. The next test the Doctor assesses the movement of the eardrum while using a probe with an airtight seal and change the pressure in the outer canal. How the eardrum moves can be significant; no movement may indicate middle ear infection as one possibility. Next the Doctor has the patient identify the thresholds or softest level of different pitches of tones that correspondto the sounds of speech.
The next part of a hearing assessment includes repeating 2 syllable words like “hotdog” at threshold and then single syllable words at the most comfortable level that the patient establishes. The percent correct of words the patients repeats at the comfortable level is also diagnostically significant and can indicate how much a patient should understand with appropriate amplification.
In order to understand the audio test results a brief discussion of tones/frequencies and levels of soft to loud in decibel (dB) is needed. Thresholds are the softest level of sound, speech or tones, that the patient identifies 50% of the time. Frequencies or pitches of the tones range from 250 Hz, which is close to middle C on the piano, to 6 octaves above. The levels of loudness are in decibel from 0 dB, which is generally the threshold that people begin to hear the tone, to over 110 dB. Normal conversation levels are about 45-50 dB and a shout is close to 75 dB. Any level louder than 95 dB requires hearing protection, i.e. a power lawn mower and table saw operate at 95 dB and require hearing protection.
Thresholds greater in numerical value than 25 dB indicate beginning hearing loss and as the value gets larger (25 to 110 dB) the hearing is poorer. In other words, the amount of speech information that gets to the brain is decreased. Speech sounds have different bands of energy at different frequencies. The combination of these energy bands tell the brain what the sound is. If the hearing loss is in the high frequency tones, a “b” might sound like a “m” and therefore the word “ball” might sound like “mall” which creates a miscommunication. Most hearing losses have some of the thresholds in the highest tones, 85 dB or greater that cannot be reached with amplification but if the other frequencies of speech are receiving the bands of speech information via the hearing aids the brain gets more information and the patient understands easier.
When considering when amplification is appropriate, the correct instrument is important. There are a number of hearing aid companies that make excellent hearing aids and are sold through different businesses. When choosing a provider, look at what the Better BusinessBureau has to say about the business you’re going to use. When choosing a product look at: are the aids digital and programable, do they have at least 20 channels, are they Bluetooth compatible, will they connect to your cell phone, do the aids talk to each other, are multiple programs available or needed, what does the warranty cover and for how long, are they covered for loss/damage. High end products are more flexible and therefore have greater controls in programing/solving problems. However, something that is less expensive may work for your needs. Where do you want to hear better? TV, on the phone, church, or multiple complex environment at work. Answering these questions will help you and your provider select a product to meet your needs. The audiologist should proceed with what the testing indicates within what the patient needs all within the perimeter of best practice.
The audiologist should be able to provide realistic expectations. Sometime the amplification does not provide all the speech sounds due to the degree of loss. This should be noted and provided to the new hearing aid patient. Often it is necessary in changing our communication skills and this is something that your audiologist is trained to teach you. For example: Speaking at a distance is problematic or with your back to the hearing aid user while you are talking. Some of those high frequency sounds, where the worse part of the lost is, only travel a few feet and don’t hit the hearing aids. We benefit from visual clues also. So sometimes looking at the hearing aid user within 5 feet will help them receive more of the speech signal. The audiologist is trained in providing more of these type of communication strategies.