Hearing aid index • Page last modified: July 9, 2021
Hearing aids are electrical devices that assist perception of speech or other sounds. We are generally in favor of hearing aids in persons with significant hearing loss. We think that life is too short to have a suboptimally functioning sense.
In essence, you need a hearing aid if the cost/benefit ratio is reasonable. An "ideal" hearing aid candidate is someone with a mild-moderate bilateral hearing loss, and who has experienced a noticeable communication handicap. Many individuals who have good hearing on one side can adjust reasonably well to any degree of hearing loss on the other side. Hearing aids are not indicated for an ear with minor hearing loss, and are also not very useful in an ear with profound hearing loss. In other words, hearing aids are usually most appreciated in people with mild to moderate hearing loss on both sides.
Hearing aids are high priced devices that are generally sold by small business people (audiologists) who are to some extent, salespeople. Hearing aids may cost about as much as a used car. It is good to have some general rules in mind when you are shopping. Generally speaking, a person is not "aidable" if they break the 50-50 rule on their hearing test-- if their PTA is > 50, or their WRS is < 50. To avoid problems, it is best not to have the same business operation test your hearing and also sell you your hearing aid as well. If someone tries to sell you a hearing aid for a "profoundly" deaf ear, get a second opinion, or bring it back after you try it out and get your money back. The general exception to this rule is "CROS" devices, which are used to send sound from the "bad' ear to the "good" ear. These can sometimes be a good idea.
Be sure that you need a hearing aid. It is said that 2/3 hearing aids go unworn. Most states have a 30 day return policy, some even longer.
Hearing aids do very little for balance, and certainly do not prevent vertigo.
|Minimal or no hearing loss, or steep drop.||Minimal or no benefit (little to gain)|
|Moderate hearing loss||Good benefit|
|Profound hearing loss||Minimal or no benefit from conventional aid, consider cochlear implant if bilateral, BAHA if unilateral.|
An example of an audiogram where a hearing aid is probably not going to help because of a steep drop is shown below.
|A hearing aid will likely go "in the drawer" for a person like this. There is a very steep drop between 1-2K, and at higher frequencies, hearing is severely impaired.|
The problem here is that there is only a small range of frequencies where making sound louder will help (between 1-2K). Making things louder at higher frequencies will cause distortion and feedback. This patient does not need anything louder at lower frequencies, so benefit is minimal.
This is a complex question that has been debated since the 30's. Essentially the idea is that hearing aids make noises louder, and it is well known that loud noise can cause hearing loss. Macrae dealt with this issue in a rigorous fashion (Macrae, 1991; 1995). The abstract of his 1991 paper states "The model implies that any noise exposure that would cause deterioration of the hearing threshold levels of a person with normal hearing would also be harmful to the hearing of a person with sensorineural hearing impairment. It follows that, in order to ensure that no deterioration occurs in the hearing of a hearing aid user, the output levels from the aid must be such that they would not cause any damage to a person with normal hearing. This constraint can be met for hearing aid users with mild-to-moderate sensorineural hearing loss but cannot be met for users with severe-to-profound loss because it would result in the provision of insufficient gain, particularly at the higher frequencies. If the model is valid, then for this group, some appropriately small amount of hearing damage must be accepted as the cost of the advantages gained from the use of a hearing aid."
In spite of this theoretical prediction, the literature does not bear out a substantial effect. For example, Podoshin and associates (1984) reported hearing results over 8 years in 114 patients aged 10 to 91 years with different kinds of hearing aids fitted in one ear only, the unaided ear acting as a control. There was no change in hearing between the aided and the unaided ear at least for 8 years.
Our take on this issue is that logically, there must be a risk of a hearing reduction from loud noise, including that produced by hearing aids, and that one should consider the (small) risks and benefits when purchasing one of these devices. To be safe, hearing aids or assistive devices should have circuitry that limits output to safe levels.
Some have suggested that hearing aids can improve word recognization through central reorganization. There is some research evidence that if you don't use it, you might lose it. Our impression is that these effects, while real, are trivial. While children have considerable plastic change to their brains, we don't think that adults will lose many (more) brain cells, if they decide not to buy a hearing aid after all.
Song et al (2011), recently studied this issue and suggested that there is no improvement. Similarly, Maniakas et al (2014) showed there was no difference in hearing between individuals who were treated for otosclerosis early on or 10 years later. Hong et al (2016) found no causal association between cognitive function, visual impairment and hearing loss. These data suggest that the idea that your hearing or intellect will deteriorate unless you buy a hearing aid is marketing hype. A corallary is that someone who suggests that your hearing will get get worse because you did not purchase a hearing aid is either misinformed or worse.
Although this idea seems bizzare, there have been some studies suggesting that hearing aids might magically improve balance. Perhaps the idea is that balance and hearing are both in the ear, and perhaps helping one will help the other. One might also think that the eyes and the ears are both in the head, so glasses might improve hearing. Hm. This is a "straw man" type hypothesis.
McDaniel et al (2018) reported that "No statistically significant differences in participants' balance were identified regardless of the presence or absence of their hearing aids during the SOT."
Audiometric evaluation -- determine type (i.e. sensorineural, conductive or central), degree, and frequency slope. Determine word recognition score with and without amplification. The evaluation should be able to predict the amount of benefit of a hearing aid, in terms of speech comprehension. Many times an office may have a unit that you can try in the office. While this will not be as good as a custom fitted hearing aid, it will give you an idea whether or not it is a good idea to proceed.
Otologic evaluation -- determines whether medical or surgical treatment is possible (i.e. wax removal). Approximately 5% to 10% of adult hearing problems are medically or surgically treatable. The percentage is higher in children if middle ear disease, such as ear infection, is the cause (www.asha.org/public/hearing/treatment/hearing_aids.htm)
Medical clearance is advisable before purchasing a hearing aid. We have encountered individuals who were fitted with a hearing aid, not knowing that they had a tumor of the hearing nerve. In general, persons with an unexplained unilateral hearing loss deserve a medical evaluation.
Organized by technology (and expense)
|Bilateral deafness||Strong hearing aids, Cochlear implant|
|Unilateral deafness||BAHA type device, CROS hearing aid|
|Partial hearing loss -- PTA > 35||Hearing aid, implantable hearing aid, assistive device|
|Minimal hearing loss -- PTA <35||Just turn up the volume. Usually hearing aid is not a good idea.|
Special features include directional microphones (CPD), noise reduction algorithms, loudness scaling, and multiple listening "programs", remote control options, "high resolution" auto-controls, speech enhancement algorithms, and feedback controls.
Organized by appearance and size
Assistive listening devices. A large variety of devices are available at much lower cost than hearing aids. Some are free. Telephone companies provide free amplifiers and ringers if patients present a physician or audiologist release. Hotels provide telephone amplifiers in 10 percent of rooms. Examples are devices that flash lights when the telephone rings, vibration devices when the doorbell sounds, flashing smoke alarms, television amplifiers, etc.
|Behind the ear (BTE). Cheapest, easiest to adjust, less feedback than other devices. Fairly visible (the model shown in the middle is from the Oticon web site). Most powerful. Fewest number of problems with wax or infections. Does not require an impression. BTE hearing aids come in many different colors to match your skin, hair, and bright colors for kids. They may be connected to external sound sources such as assistive listening devices (directional technology, FM systems, CROS/BI-CROSS hearing devices) and telephones and televisions using a t-coil.|
|Post-auricular canal (PAC). A hybrid between BTE and CIC. Almost invisible, easy to fit and maintain. The pictures are from Sebotek.|
|In the ear (ITE). Low visibility; harder to put in than PAC or BTE. Powerful and still fairly easy to adjust. This type of hearing aid is custom made to sit flush with your outer ear and yet still is easy to manipulate. ITE hearing aids also come in skin colors and can also be equipped with directional technology and t-coils.|
|In the canal (ITC). Very low visibility. Clearer than BTE. Lower power so not suitable for persons with more severe hearing problems. Patients with tremor or poor eyesight are not good candidates. ITC hearing aids are also matched to skin color.|
|Completely in the canal (CIC). This is the smallest hearing instrument available today. Patients with tremor or poor eyesight are not good candidates for the CIC. It is best used for mild to moderate hearing losses. It fits snugly into your ear canal with a tiny filament that is used to remove the instrument. The outer surface of the CIC is made to match skin color.|
There are also Body/Eye-glass styles (< 1% of all hearing aids), low-profile, half-shell, and canal types.
The PAC/BTE type hearing aids are particularly simple -- very little fitting is needed -- no ear mold, and can practically be used "off the shelf". Of course, they should be "equalized" for the hearing deficit that the patient has. This "equalization" process requires someone to have equipment that "talks" to the digital hearing aid. Some models of BTE now can be adjusted through ones cell phone. This seems to us like a very good idea.
Advantages of Binaural hearing aids
- Improved understanding -- information from one ear may be different from other ear
- Localizing sounds -- information from both ears allows one to triangulate a sound source
- Keeps both ears active (use it or lose it)
- Reduces jarring effects of loud sounds when divided between ears (improves dynamic range)
- Allows one to understand speech from either side
Binaural amplification means hearing aids on both sides. If you have trouble with hearing on both sides, this is obviously better than one side only, but more trouble to keep maintained. Binaural amplification minimizes impact of "head shadow" drop off, improves sound localization, widens dynamic range, and costs twice as much. Some individuals with bilateral hearing impairment do worse with two aids than one. This usually happens when the ears differ appreciably in hearing impairment, and occurs because the noisy/distorted/louder input from the poorer ear interferes with hearing from the better ear (i.e. binaural interference, see Baron, 2002). Nevertheless, most people with age related hearing loss opt for binaural hearing aids.
There are some very nice technologies that you can use with your aid. T-coils and FM systems are methods of getting very clear sounds with no feedback. You should investigate these if you are OK with wearing a larger hearing aid.
|BAHA (bone anchored hearing aid). This type of hearing aid works well in persons with severe unilateral hearing loss. The image to the left, from Prosper hospital, shows how a button is inserted into the bone of the skull above the ear. The middle image is from //www.islandhearing.com/bone_anchored_hearing_aids.htm, by Island Hearing. The device is attached to the button within the skull. It is very unobtrusive (once the hair is put back into place).|
Hearing aids are typically not covered by Medicare or commercial insurance and pricing varies according to the manufacturer, vendor, and service arrangements. According to Kirkwood (2005), in 2004, the average price of a hearing aid was $1776. These prices are taken from an article on management of hearing loss by Bogardus et al, 2003.
|Hearing Aid Type||One ear||Both Ears|
|Conventional (Analog, non-programmable)||850 -1500$||1400-3000|
|Programmable (Analog)||949 -2000$||2200-4000|
There are numerous brands and variants. In general, smaller devices, such as the CIC devices mentioned above, are more expensive, and newer/more complex circuitry is also more expensive. We are not in favor of CIC aids- -we think BTE is the best right now. Compression circuitry in analog aids is more expensive (but definitely a good idea). Directional microphones cost more, but are also a good idea. Greater user control is also usually more expensive. Bilateral aids are often but not always better (Baron, 2002).
Hearing aids are very expensive and many people choose not to use them because they can't afford them. Bainbridge et al reported that a 28 to 66% greater prevalence of hearing aid use among more affluent older adults (2014).
As hearing aids are generally not covered by insurance and typically cost in the $1000's, we recommend that you think about purchasing one carefully. On the other hand, hearing is a very important sense and you can be oblivious to much important information as well as very annoying to your family when you can't hear.
There are many ways to obtain a hearing aid. The most common method is to visit a dispensing audiologist who can test your hearing, recommend an appropriate device, and assist in the maintenance. Another common method is to visit a "big box" provider like Costco, who more basic evaluastion services but devices that are still suitable for most persons.
We think that it is best to find a reputable source for your hearing aid, and also a source that will offer a reasonable selection of devices. An office that offers both a physician evaluation as well as an audiologist to do the hearing test (but not to dispense the device) is best -- we have encountered people fitted with a hearing aid that actually had a tumor on the auditory nerve. Usually this kind of mistake can be avoided with physician oversight.
Over the last few decades, the big push with hearing aids has been to make them smaller. This has been accomplished rather well, and we think that the next big push needs to be in improving performance. Features that we would love to see routinely in hearing aids are the following:
- Interfacing to other devices -- WiFI, radio, cell-phone, computer. Presently many hearing aids use clunky FM or noisy AM t-coil systems rather than contemporary bluetooth or Wifi interfaces. Recently though, Blue-tooth is available in some high-end aids. Some hearing aids can be configured through smart-phones as well. This is a big advantage.
- Multisensory convergence - we would like to see a hearing aid add-on that would also put up a visual display of a speech recognition system. In other words, something similar but smaller than the system that legal secretaries use already. Some progress has been made on this in a research setting (Zekvold et al, 2008)
We think that, for the most part, people looking for a hearing aid should find a dispensor that is close enough to them that they can easily get their hearing aid serviced, cleaned and checked. In more rural areas where parking and traffic is less intense, larger distances seem reasonable. You should consider how far the office is from your house or place of work as return visits may be required for cleaning and repair. In Chicago, Costco is a reasonable place to get good quality hearing aids.
An exciting recent development is an ability to provide hearing to some bilaterally deafened individuals through implantation of a device which directly stimulates the hearing nerve (actually the spiral ganglion). Although this device is not generally considered as a "hearing aid", it performs the same purpose for individuals with severe hearing impairment involving both ears. For more details, see the cochlear implant page.