Custom hearing device products do not have IP (Ingress Protection) ratings, only behind-the-ear devices do. For moisture, the highest score a product can receive is an 8, which means it is waterproof. Custom devices between ReSound or Phonak are likely to be similar, with a rating of 7, which means it can be submersed in water for up to 30 min and still work. Because the battery door is not sealed, the custom device cannot be waterproof. If your custom device is submerged in water, it will likely be functional, but you'll want to be sure to throw out your old battery. If you have a drying jar or a bag of rice, you can place your device in there overnight and both will wick moisture out of your device.
Unfortunately custom hearing aids do not have an I.P. rating to objectively judge the moisture resistance (behind the ear instruments do have this rating for comparison). Moisture issues can occur for many reasons including vent size, personal hygene and environmental factors to name a few. From my clinical experiences I have not seen a great deal of difference between the two. Both Resound and Phonak make fine products and I have found them to be extremely reliable.
I generally agree with most of the responses but if you stop and think a moment, the most vulnerable entry point of moisture into an ITE hearing aid is through the battery compartment. Hansaton is the only manufacturer I am aware of that manufactures an ITE hearing aid model with a sealed battery compartment. They do this only for their rechargeable ITE. I would think that would make the unit less prone to moisture ingress. Very often moisture ingress is not directly from splashing fluids but from sweat and condensation in the air. The more humid climates where people enter and exit into air conditioned spaces are more likely culprits.
All custom hearing aids are more subject to moisture, dirt, wax, and debris than a behind-the-ear style device. IP ratings are available for Phonak BTE devicesrange from 57-68 for their BTE devices. I would imagine the custom products are pretty similar. Regardless, you would never want to swim or bathe with a hearing instrument in your ear, but if you are concerned about sweat or humidity, you can purchase a dry kit (some use a desiccant tablet and some are electronic) to serve as a dehumidifier and pull out moisture. You would need to remove the battery before putting any hearing aid into a dry-aid device. Good luck!
I have found that moisture issues with custom ( in the ear) hearing aids are very much influenced by how well the manufacturer is able to vent the aid. This is influenced by the size (power) of the speaker (receiver) that the patient needs as well as the size of the computer chip. I have no personal experience but speculate that the internal hardware needed to create the Made For I-Phione Resound aid could be larger than Phonak's aid meaning that the Resound aid would have less venting and pottentially more moisture.
E Stacey Frank, audiologist
As my colleagues have noted, all hearing aids are susceptible to moisture. If you wear hearing aids now and have a history of the hearing aids failing from moisture, the use of an electronic dry aid kit, sich as Dry and Store, would be beneficial.
We cannot comment to much on the specifics of the Phonak Virto, as we have very little expeience with that hearing aid. We can tell you that all of our providers are very impressed with ReSound's iSolate Nanotechnology coating, which protects all components of their hearing aids from moisture and dust. ReSound actually applies this coating under vacuum condition, so the nanocoat polymer enters every nook and cranny of the hearing aids. We do believe that ReSound's current moisture resistance is superior to Phonak.
We have had patients accidentally wash their hearing aids (not something we recommend) and still worked. The husband of one of our audiologists recently dove in the ocean head first wearing his ReSound LiNX2 hearing aids (not something we recommend either). He let them dry out for 24 hours and was happy to have them continue to work.
About the same in my opinion too due to the reasons explained by colleagues here.
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