The topic of moisture and hearing aids goes on.
It is a big topic and one that I discuss a lot with patients. Hearing aids are susceptible to all types of moisture and their is no way to avoid it completely. The best you can do to protect your investment and your instruments is to maintain an acceptable level of dryness and that can be done in a number of ways.
Sometimes I am asked if there is such a thing as a waterproof hearing aid. There answer is “none that have been successful.” Part of the reason why hearing aids continue to have moisture issues is due to the battery. The batteries in hearing aids are air activated… that means that they need to be exposed to the air to work. If the hearing aids were completely sealed from air, the batteries would not function (consequently, they cannot be easily sealed from water for the same reason). Also, if the aids are sealed and moisture gets in the aid it won't be able to escape back out. If moisture becomes trapped inside the hearing aid you then have battery corrosion issues and possibly moisture related break down of the amplifier, and/or processor (or other delicate parts of the hearing aid). So, some leakage of air (and water) is necessary for a hearing aid to function. Perhaps in the future with sciences like Nanotechnology we will eventually be able to create a membrane barrier that will not allow moisture in but will allow moisture to escape and air in for the battery. Perhaps with improvements to the batteries (such as the new rechargables that are coming out) we will no longer need zinc-air battery cells for power. Some manufacturers are starting to play around with Nanotechnology and it is a fascinating science. I believe consumer will see many of their concerns slowly addressed as appropriate solutions are put on the market.
As for moisture prevention solutions…
Let me first say, you cannot swim with your hearing aids in but if you are going to wear your in-the-ear (ITE) aids in or around the pool or other potentially hazardous places, at the very least find a head wrap called EarBandit. This will also keep the aids from falling in the water. For those of you that wear behind-the-ear (BTE) hearing aids, you can also use the sweatband or EarGear products. These are not waterproof options and you still should avoid getting the aids wet… but they will provide splashguard. So, you can relax a little and have some fun. When you are done for the day at the pool… let your hearing aids dry out for 8 hours before wearing them again. Open the battery door and put in a dry, safe place. Never use hair dryers, heat lamps, hot air guns, microwaves or ovens to dry the aids.
Aids that are frequently exposed to water/sweat need a gentle, even, dry heat to remove moisture build up and this can only be found in electric drying kits. This is very important for those on the list that are profuse sweaters and love water sports. Even those who live in humid, muggy climates should consider an electric drying kit. If you are very active or if you sleep with your aids in (you know who you are) you need to give the aids a break once in a while and dry them out. Different companies offer different features in their drying units. You will find that most have a desiccant bar/bag/pouch and a heat source. Some also have ultraviolet light, thermoplastic heat and vibratory or mechanical spin dry cycles. Some are very simple, others more complex. Check to see if your audiologist has any demonstration units in their office. I've tried many drying units myself and I have always liked the Dry & Store brand. However, there may be a different unit that will fit your needs better. For BTE users on the list. Don't forget your tubing needs to staydry. Moisture sneaks into the hearing aid through the earmold and up the tubing. You'll see little bubbles around the bends of the tubing. This is best removed by disconnecting the earmold from the earhook/hearing aid and pushing dry air through the tube. Remember if you try to blow into the tube with your mouth you are only re-introducing the moisture from your own breath. So, it is better to have a “earmold blower” which looks like a nasal bulb or other compressed air. Be cautious with canned air… it can contain chemicals that can contain irritants that affect the respiratory system and cause skin sensitivities and possibly be toxic to your health.
Even if all the information above is not applicable to your situation because you are not active or don't sweat, you'll still want to at least open that battery door up overnight and have your aids professionally cleaned and dried twice a year.
Feel free to contact me for more information or to ask specific questions about this topic. firstname.lastname@example.org