Rachel Magann Faivre, AuD 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... Read more
Sheri Gostomelsky, AuD The answer lies in how deep the device can be built to fit in your ear. Most of the ear canal has cartilage under the skin, however the last third of the ear canal is bone. If the device reaches the bony portion of your ear, the echo or occlusion can be eliminated.