What Level Of Hearing Loss Requires A Hearing Aid?
Hearing loss may affect over 13% of the population at any given time, with the most common form of hearing loss being temporary and treatable. The Mayo Clinic defines hearing loss, impairment, and deafness as the partial or total inability to hear sounds.
Most of the time, hearing loss that is treatable stems from Conductive Hearing Loss, which stems from a blockage in the outer or middle ear, or a disruption to the eardrum or middle ear bones known as the hearing conduction system.
Treatment for hearing loss is best determined with a series of tests by a specialist and can range from antibiotics to a medical procedure, with some needing the assistance of some form of a hearing aid. A hearing test provides important information regarding the specific type of hearing loss, not just that the person cannot hear.
The Three Types of Hearing Loss
Hearing loss is classified into three categories, Conductive Hearing Loss, Sensorineural Hearing Loss, and Mixed Hearing Loss.
Conductive Hearing Loss (CHL) is caused when there is a blockage in the outer or middle ear, or a problem with the conduction system responsible for transmitting sound to the inner ear. CHL may be the easiest form of hearing damage to remedy and can be as simple as removing earwax which is a natural oil that is produced by the skin of the ear canal. A thorough evaluation from a primary care physician can determine the severity of conductive hearing loss and an Ear, Nose and Throat specialist is best suited to offer the patient options as to how to fix it, if it is possible.
Sensorineural Hearing Loss is when damage occurs in the inner ear and affects the auditory pathway, the cochlear hairs, or auditory nerves. Hearing loss that stems from this type of situation is permanent and may require more serious medical attention and the use of hearing aids. In extreme cases, the hearing can be restored with a cochlear implant or other new electronic device.
Mixed Hearing Loss is a form of hearing loss when there is a combination of outer, middle, and inner ear damage. As with Sensorineural Hearing Loss, Mixed Hearing Loss sufferers will incur permanent hearing impairment. The mixed hearing loss requires detailed evaluation by an Ear, Nose and Throat specialist who can determine if repair of the conductive portion of the hearing loss may be worthwhile even though there may still be sensorineural hearing loss remaining. In some cases, restoring the conductive hearing loss may be done solely to allow the person to better use hearing aids.
Hearing loss can occur in one ear, unilateral, or in both simultaneously, known as bilateral. Often with hearing aids, it’s recommended to have a device for each ear to keep sound equilibrium without any potential feedback, regardless of whether hearing loss is unilateral or bilateral. Using hearing aids in both ears allows for what is known as localization of sounds. In other words, the person can tell from what direction a sound is coming from.
Common Causes of Sensorineural Hearing Loss
Sensorineural hearing loss can occur from any number of causes ranging from genetic predisposition to hereditary factors and aging. In fact, over ⅓ of all adults over the age of 65 years of age experience some form of hearing loss.
For adults over 75, the rate of hearing loss increases to 50%. Aging is one of the main culprits of hearing loss, while environmental factors such as exposure to loud noises and machinery is another.
Other causes of hearing loss may stem from defects in the ear canal, frequent ear infections, head trauma, or even colds, or allergies.
The Four Degrees of Hearing Loss
There are four degrees of hearing loss, ranked from mild to moderate, severe, and profound. Sound is measured in units known as decibels, abbreviated as dB.
Mild hearing loss affects sounds in the 25-40 dB range. Softer sounds are difficult to discern for the sufferer. Examples of sounds in the range of mild hearing loss are normal breathing (10 dB), whisper from over five feet away (25 dB), to sounds in a quiet library (40 dB).
Moderate Hearing Loss affects sounds in the range of 40-75 dB. In this range, standard speech patterns and conversations may be difficult to hear, especially around many prevalent noises, such as in a crowded room. More everyday sounds, such as a running refrigerator (50 dB) to a washing machine (70 dB). Daily living is more difficult with Moderate Hearing Loss.
Severe Hearing Loss’s definition is familiar sounds that are almost impossible to hear without some form of hearing aid. The unclear range of decibels is 60-90 dBs, and practically any familiar sound is indecipherable without the use of a hearing aid. Everyday examples in this range of hearing loss are an electric toothbrush (60 dB) to a subway train (90 dB). It cannot be understated the risk of danger of injury that may result from Severe Hearing Loss.
Profound Hearing Loss is the most debilitating of the four primary levels of hearing loss. Any sound that is less than 90-120 dB is unable to be heard. Typical sounds in the 90+ dB range from heavy machinery (100 dB) to a car horn (110 dB) and louder. Profound hearing loss can contribute to many other safety concerns for the sufferer and inhibit a better standard of life.
How A Hearing Aid Works
Hearing aids are engineered to absorb sound and retransmit it at a greater volume than received. A hearing aid’s basic design comprises three components, a microphone, an amplifier, and a speaker to transmit sound through parts of the auditory canal.
This amplification process can be either analog or digital, and there are hearing aids for either amplification. Analog hearing aids transmit sound as one continuous wave and can be challenging to adjust in various settings as noise level changes. A digital hearing aid translates sound into a numeric value and can adapt noise to appropriate levels once the device is programmed. A hearing aid can fit outside the ear or be implanted, depending on hearing loss and the damage that has occurred.
Types of Hearing Aids
There are three main types of hearing aids, the behind-the-ear (BTE), in-the-ear (ITE), and in-the-canal (ITC). Behind the ear is a device that snuggles behind the ear lobe and has a mold covering the outer ear. In some designs, known as a “mini,” the hearing aid base fits behind the ear while a tiny cable runs into the ear canal. The “mini” design is more aesthetic and a more comfortable fit than the traditional design.
An in-the-ear type of hearing aid is engineered to fit inside the ear canal and is prescribed primarily for moderate to severe hearing damage. One key feature of this design is that instead of a microphone, a telecoil can absorb sound. The benefit of a telecoil is that it uses magnetic coils in lieu of the microphone. The assistance of “induction loops” can help the user differentiate and filter ambient sound in public places, especially when Bluetooth or other technologies are present.
The third design type of hearing aids is an in-the-canal device. With this type of device, the hearing aid is implanted in the middle ear toward the inner ear to augment sound to the damaged cochlea. This design is for more severe hearing loss and, since it is embedded, requires medical attention to change or alter the device.
Hearing aids are engineered as either analog or digital. With an analog device, the sound is amplified in a continuous wave pattern, the sound is continuously amplified, and differentiating sounds can be less precise. Analog devices don’t separate distinct sounds such as speech from the ambient noise in a room. Preferably the analog device only amplifies the sounds as much as the user would like them.
Digital hearing aids, on the other hand, can absorb sound and translates it into numeral code, much like a binary computer. The design of digital hearing aid allows the user to increase the sound frequency and amplification independent of the ambient noise, making subtle sounds more discernable than general noise.
Level of Hearing Loss That Requires A Hearing Aid
If you have experienced hearing loss, it’s necessary to get a complete evaluation to determine the extent of hearing loss and eliminate any additional health concerns.
A primary care physician can ascertain if the patient will need to seek more evaluation from a specialist, whether the hearing loss can be corrected with antibiotics, other medical procedures, and what type, if any, a hearing aid is needed.
Depending on the individual prognosis, hearing aids consider every diagnosis from mild to moderate, severe, and profound. While a hearing aid will assist with sound amplification, unlike glasses that will magnify and correct vision issues, hearing aids will not correct the damage. Eyeglasses have corrective lens while hearing aids do just that: aid hearing.
Hearing loss and impairment can have subtle side-effects such as irritability, social withdrawal, fatigue, and other mental health issues. A hearing aid will give the user a better standard of life with mild to moderate hearing loss.
Issues stemming from hearing loss can include:
- Irritability, especially in crowded environments
- Confusion and uncertainty in differentiating different sounds, noises, and speech patterns
- The conversation is incomprehensible and muffled.
- Safety concerns around dangerous machinery
- Depression and Social withdrawal
- Sub-standard way of life
Diagnoses of more severe hearing damage will require aggressive remedies such as implants and ITC types of hearing aids. These devices will be surgically implanted and will need occasional follow-ups for maintenance. The wearer will be unaware of the implant; however, the benefits of being able to hear everyday noises, from speech to machinery, adds a quality of life that otherwise is lost. For the person to reap the most benefit from these types of hearing implants most people require special training with an audiologist, almost like having to see a physical therapist after knee or hip surgery.
With advancements in design and function, the hearing aids on the market today are smaller and more comfortable than previous models. By using the telecoil instead of a traditional microphone, the hearing aid is smaller and more compact.
With the telecoil design, advancements in engineering allow the user to block out some of the ambient noise from more traditional hearing aids and give the user more comfort and individualized hearing amplification needs. A telecoil also allows for Bluetooth technology to be utilized by the wearer to transmit directly from other Bluetooth devices.
Additionally, the compact design’s comfort eliminates the sense of stuffy or blocked ears, known as occlusion, which is no longer an issue with the newer, smaller systems. Older designs used vents to allow some air sounds to pass through unimpeded.
Drew Sutton M.D.
Drew Sutton, MD is a board-certified otolaryngologist. He has extensive experience and training in sinus and respiratory diseases, ear and skull base surgery, and pulmonary disorders. He has served as a Clinical Instructor at Grady Hospital Emory University for more than 12 years.