Dr. Martin has been a dispensing audiologist in private practice in the San Diego area for more than 30 years. He has been writing Nuts & Bolts since 1989.
How often do you see hearing aids clogged with earwax: twice a week or twice a day? I have seen thousands of dead hearing aids during my 35 years of practice from small amounts of earwax getting lodged in the sound tube, preventing transmission. Remove the wax, and the aid is fine.
This problem plagued us when I started in this business, and is a major headache today. Numerous solutions have been implemented, but to my knowledge, no simple, effective solution keeps wax out of the sound tube. All hearing aid practitioners must be skilled at cleaning impacted sound tubes.
I asked HJ readers in September what they use to remove wax from sound tubes. (See FastLinks.) I received many great ideas. Earwax has a mysterious nature, and can be found in seemingly impossible locations. Our tympanometer was repaired last year because the air pressure tube was plugged with earwax 12 inches away from the ear probe. What kind of dark magic moved the wax one foot from the ear?
One patient came in with a clean ear, yet her hearing aid was plugged with earwax. How did this happen? Another patient wearing a behind-the ear (BTE) hearing aid has a small amount of earwax lodged in the upper curve of the BTE's hook. It was approximately two inches from the earwax in his ear canal to the ear hook. How did the wax get there? I believe the answer is sublimation.
We studied the transformation of substances in grade school through the three physical states: solid, liquid, and gas. Ice typically goes from a solid to a liquid, then to water vapor, which is a gas. The exception to this is sublimation. When a substance sublimates, it passes directly from a solid state to a gaseous state (vapor) without going through the liquid state. People who live in cold climates know all about this. Snow does not need to melt to get lost in the atmosphere; it sublimates directly.
The earwax in my patients’ hearing aids was not put there by ghosts, dark magic, or little gremlins. The wax moved as vapor from the ear to the hearing aid. The glands in my first patient's ear canal made a tiny amount of wax that found its way to the sound tube, even though it was not visible. The vaporized earwax worked its way through the second patient's ear canal, into the tube on the earmold, and then to the hook attached to his BTE — a distance of about two inches. A temperature change caused the vaporized earwax to condense in the hook and block the passage of sound.
Years ago I discussed this topic with Robert Oliveira, PhD, a member of our professional community, Hearing Components. Dr. Oliveira was trained as a chemist, and he knows more about this topic than anyone I know. He taught me about sublimation.
I do not want to suggest that earwax typically travels by sublimation. The wax production glands in the ear canal are located in the same zone as the canal end of the hearing aid or earmold. Most of the time, the patient pushes the wax into the hearing aid when inserting the instrument.
REMOVING WAX FROM THE SOUND TUBE
Manufacturers supply patients with a small cleaning tool with a wire loop on one end and a brush on the other end. It is possible to use the wire loop to remove impacted earwax in the sound tube, but if the patient is not careful, the loop pushes the wax deeper, aggravating the problem. Hearing healthcare professionals need a tool to insert into the sound tube, get behind the earwax, and pull (or pick) the wax out without damaging the sound tube. The tube's tiny size requires a single-stranded, thin, sturdy wire with a tiny hook on the end. If the wire's diameter is large, it will push the wax and debris deeper into the tube. I use this tool under a good reading light while wearing glasses designed for close field work.
Rotate the hook on the end of the wire to the side of the tube when inserting it through the wax plug. Avoid pushing debris into the tube as much as possible. Once inserted, rotate the hook to get it behind the wax and pull it out.
Over the years I have made myself a variety of different tools, or picks, for this purpose. A small, 22-gauge hypodermic needle can be converted into a wax pick by bending the end of the needle to make a hook. (Figure 1.) The problem using hypodermic needles is that the sharp peak can tear and cut the sound tube.
Usually I modify the manufacturer's wire loop tool by cutting the wire in half and pulling out one of the strands. This leaves a little hook on the end of the wire. (Figure 2.) This single-strand tool is better than the full standard, but the wire is not held in place well and tends to twist when cleaning the sound tube.
Wayne Jacobson, BC-HIS, in The Dalles, OR, sent me his design for a wax removal tool. Pull out one end of the wire from a standard wire tool and straighten it. Bend the wire 90 degrees twice. (Figure 3.) Put a small dab of plastic patch on the end of the tool to cement the wire onto the small plastic handle. (Figure 4.) Plastic patch is made by mixing a small amount of super glue and polymer paste used in hearing aid repair laboratories. Mix a small amount of this material on top of several sheets of scratch paper. Use a small screwdriver to mix the material and move it onto the wax removal tool.
The two 90-degree bends and plastic patch allow the wire to be held securely in place. The plastic patch prevents the wire from twisting and turning. Bend the end of the wire over to make a tiny hook after the adhesive dries.
I have been asked if using a long, straight, single-stranded wire to clean sound tubes increases the danger of perforating the receiver's diaphragm. I called several manufacturers and received conflicting information. Regardless, the hearing aid is already dead if no sound is coming out because the sound tube is plugged with wax.
* See Dr. Martin's September 2011 article at http://bit.ly/NBsept2011.
* Read Dr. Martin's past columns in a special collection in The Hearing Journal archive at http://bit.ly/HJMartin.
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