Open fit hearing aids or devices were developed to treat the very common middle to high frequency hearing loss. People with this type of hearing loss can hear low frequencies normally, but struggle to hear middle and high frequencies. This often results in hearing but not understanding. Open fit hearing devices are designed to boost the higher pitched sounds while preserving natural low-pitched hearing. They have become one of the most popular hearing device styles due to their small size, excellent comfort and great sound quality. The best styles use a speaker that is placed directly into the ear canal.