CROS aids are designed for unilateral hearing loss--a microphone on one side "pipes" sound to other side, where hearing is better. Recent improvements in technology has made them much better through use of digital and wireless technology (Ryu et al, 2015).
Nevertheless, most people dislike CROS aids. The reason for this is probably because one must put a device in ones "good" ear. More stuff to keep track of, batteries, etc. Often persons who have good hearing on one side just "make do" with their one good ear, and don't elect to get anything.
The main alternative to a CROS aid is a BAHA type hearing aid. These devices are less cumbersome than CROS aids, but require surgery and good hygiene.
The WiFi Mic is a digital wireless CROS/BiCROS system that uses wireless technology to transmit sounds from the side of bad ear to the better ear on the opposite side. With the Unitron system, the patient would wear BTE (Behind the ear)or ITE (In the ear) style hearing aids behind both ears. The device on the bad ear has a microphone that picks up the sound and transfers it to the hearing aid on good ear, using wireless technology. The sound is then processed by the hearing aid on the good side and delivered to the better hearing ear. Unitron offers this product is a number of technology levels. You can get the Unitron WiFi Mic as an entry level hearing aid with fewer features or as a premium product with more features and greater flexibility.
The WiFi Mic is available with the following circuits (ordered from entry level to premium technology).
· Unison 3 – 3 channels; 3 programs; Wide Dynamic Range Compression (WDRC) and linear limiting.
· Unison 6 – 6 channels; 3 programs; WDRC, ASP noise compression, adaptive compression, and linear limiting.
· Conversa NT – 16 channels; 3 programs; 4 level processing as in the Unison 6 with the addition of the automic, which switches automatically between the omni and directional microphones*; and wind noise manager.
*automic is only active with the WiFi Mic is not active. In other words, automic is only usable if there are situations in which you are using the hearing aid on your good ear, without transferring any sound from your bad ear.
Directional microphones are available on all three levels. With the Conversa NT the hearing aid switches between omni and directional automatically. With the Unison 3 and Unison 6, the user must push a button on the hearing aid to switch between directional and omnidirectional microphones.
The CrossLink is a device that can be ordered with new hearing aids or attached to most other manufacturers BTE hearing aids. This is an ideal solution if you have recently purchased BTE hearing aids and need to adapt them to a CROS/BiCROS system. Unlike Unitron, Phonak’s system is not integrated and does not have custom ITE CROS/BICROS hearing aids available. However, because the system is not integrated, there is great flexibility is the level of technology. The CrossLink can be fit with any of the following Phonak circuits (in order of least to most sophisticated technology):