Open fit devices Hearing aids

Open-fit" or "Over-the-Ear" OTE Hearing aids are small behind-the-ear type devices. This type is characterized by a small plastic case behind the ear, and a very fine clear tube running into the ear canal. Inside the ear canal, a small soft silicone dome or a molded, highlyvented acrylic tip holds the tube in place. This design is intended to reduce the occlusion effect. Conversely, because of the increased possibility of feedback, and because an open fit allows low frequency sounds to leak out of the ear canal, they are limited to moderately severe high frequency losses. Whilst the design approach is attractive to a general hearing aid user where they fall into the category to be considered fitted with one of these types of hearing instruments it has to be taken into account that Open-fit devices can by their design have problems when connected to Assistive Listening Devices (ALD's). This is due to the open-ear effect and that the user would hear Low Frequency sounds normally via no Occlusion whilst the hearing aid filters and provides the high frequencies. When a ALD's such as a Wireless FM system are provided to help a hearing aid user to hear over a distance in some cases only the high frequencies are provided to the user and the Low frequencies are lost over distance. This can easily be verified by taking different open ear Hearing aids and measuring their Output Frequency Response using a hearing aid Analyzer and then comparing the output when connected to ALD device and observing if any considered Gain in Low Frequency has been provided

Open fit devices Hearing aids