If you wear hearing aids, more than likely you have experienced hearing aid feedback. That annoying, alarming squeal that seems to be present at the wrong times, is sometimes an unfortunate reality of wearing the devices. However, it can be minimized or even eliminated by understanding what causes it and by learning how to make a few small adjustments. This article addresses the problem of hearing aid feedback and its solutions.
What’s that Squealing?
Audio amplifiers, from the tiny ones used in hearing aids to the huge ones used for outdoor concerts, are susceptible to distortion if the microphones are too close to the speakers.
- The amplifier’s output, being picked up by its input and then re-amplified causes the distortion
- Squealing, shrieking or whistling is what distortion sounds like
Consumer demand forces the hearing aid industry to design and market the smallest electronics package possible when it comes to hearing aids. This means the microphones are inherently close to the speakers to begin with, but we’ve got a few tricks up our sleeves to deal with that.
How Do I Stop the Squeal?
In most cases, it is quite easy to stop the squealing.
- Make sure that your ears are free of wax by using home remedies, seeing an Ear, Nose, Throat Specialist or with Miracell.
- Make sure the hearing aid sits comfortably behind the ear and that the dome is snugly inside the ear canal.
- If you’ve determined that your tube may be too short call us during your trial period and we will send you a longer one for free.
- If you’re free of wax and have proper tube length try one of the larger, closed domes with the “mushroom on top of mushroom” style.
Leaks
Sound is like water in that it can be piped from one point to another. A sound leak in a pipe is just as bad as a water leak because it will allow sound to leak and not be delivered to its intended destination. An undetected leak in the right spot, might easily redirect sound back toward the microphone and produce unwanted feedback. All hearing aids deliver their output sound through a tube, which can range from an eighth of an inch to a couple inches long depending on the model of hearing aid. They are susceptible to being plugged with earwax and must be cleaned regularly. While cleaning, it’s important to avoid using sharp cleaning tools that might puncture or threaten the integrity of the sound tube. We suggest using a lighted magnifying glass to closely inspect your hearing aids often.
Physical Fit
Comfort is first and foremost since ears are tender and easily injured. Correct length tubes, and diameter domes, are essential to comfort. A proper fit directs the sound toward the eardrum. An improper fit might be directing the output sound at the wall of the ear canal, causing more sound to be reflected back toward the microphone.
Domes
Soft, pliable domes are used with both BTE and RIC hearing aids that are fitted with small tubes, or wires, to deliver sound into the ear canal. These mushroom-shaped devices come in various diameters and varying sizes of vent holes in the mushroom’s skirt.
- Domes that are too big may cause low-grade earaches
- Domes that are too small may cause tickling and/or feedback
- More open domes reduce background noise but increase chances of feedback
- More closed domes increase overall volume and reduce feedback
We encourage our customers to experiment with different dome configurations to get the proper balance of sound that’s right for them. It is also important to note that there is a dramatic difference in the sound of a hearing aid when using a closed dome versus when using an open dome. Keep this in mind when considering which domes to use with your hearing aid and make sure your expectations are set accordingly.
Volume control
Some situations create better feedback paths than others. Being in a small car with the windows rolled up for example. Using the volume control is the quickest method of reducing feedback but it’s more of a band-aid than a solution. We suggest controlling overall volume by choosing a dome configuration that gives you enough reserve volume you don’t feel volume starved.
Trimmers
Your hearing aid might be equipped with one or more small adjustment screws called trimmers. They can be a big help in adjusting the sound and eliminating feedback.
H Trimmer - limits the High Frequency (HF) output of a hearing aid. The reasons for limiting HF are:
- To combat squealing or acoustic feedback
- To increase acoustic comfort by limiting how loud unpleasant HF noises such as rattling silverware and dishware can get
Caution: Speech clarity depends on a hearing aid’s ability to make high-frequency consonant sounds audible to the wearer, above the environmental noise. Using an H trimmer to limit HF sounds too much does just the opposite.
L Trimmer - limits the low frequency (LF) output of a hearing aid. The reasons for limiting LF are:
- To reduce background noise
- To increase speech discrimination in noise
Caution: The majority of sounds we hear are within the frequencies affected by the L Trimmer. Too little LF can cause the wearer's voice to sound occluded and unnatural. Also, music sounds tinny when LF is reduced too much.
P Trimmer - Lowers the maximum volume or power of a hearing aid’s output sound. The reasons to limit a hearing output power are:
- Acoustic comfort
Caution: Our ability to tolerate loud sounds tends to decline with age and the amount of hearing loss present. One factor in the rate of decline is how often a person is hearing loud sounds. In other words, if you not being exposed to louder sounds on a semi-regular basis, your inability to tolerate them may deteriorate at a more rapid pace. We recommend keeping loud sounds on the edge of being uncomfortable.
Not long ago the rule of thumb for hearing aid wearers was to “turn them up until they start squealing” and then back off a touch. That is not so today. The hearing industry is advancing quickly and today’s technology is getting closer to curing the squealing problem.
With the right hearing aids in combination with the right tubes and domes, even people with severe to profound hearing loss can get more volume from their hearing aids than they can stand without feedback. The key is understanding how to make any adjustments needed to bring your make your hearing aids comfortable and functional for you and lifestyle.
Good luck on your journey to better hearing and stay tuned for more messages full of great information to help you hear well and protect your investment.