What is a CROS System?
It is a type of hearing aid system used for people with deafness in one ear that cannot be corrected by a hearing aid.
CROS (contralateral routing of signal) is a type of hearing aid system used for people with unilateral hearing loss, where the deafness in one ear cannot be corrected by a hearing aid. Situations where an ear may not benefit from a hearing aid include:
- The ear cannot hear at all (dead) or cannot understand (poor speech discrimination), even with a powerful hearing aid
- It is often infected (repeated otitis), so hearing aids are contraindicated
- Etc.
Criteria for hearing aids with CROS system (controlateral routhing of signal):
- Deaf ear cannot be equipped with a hearing aid and the other ear has normal hearing or hearing loss that can be corrected with a hearing aid.
The system sends sound from the ear without a hearing aid to the “better” ear (contralateral ear) to eliminate the head shadow effect*. That way, the person can understand speech no matter which side the speaker is on. This system is often useful when driving or having conversations in a group.
Here’s how it works:
A microphone is placed on the ear that cannot hear or wear a hearing aid. A wire is attached to the microphone, connecting it to the hearing aid on the “better” ear. This allows speech to be sent to the “better” ear. The wire, which runs behind the back of your neck, can easily be hidden in hair or a shirt collar. There is also a wireless version of the system, which uses MF waves to send sound to the hearing aid.
The RAMQ’s Hearing Devices Program covers the costs of a wired CROS system for those eligible. If one of your ears has hearing loss that cannot be corrected with a hearing aid, you can discuss this option with your audioprosthetist. They will be able to give you more information. Many people who have tried this type of system have been surprised at just how useful it is.
For more information, don't hesitate to talk to an audioprosthetist practicing in a Lobe clinic by calling 1 866 411-LOBE (5623).
*Definition of head shadow effect: Obstacle of the head during the passage of sound to reach the contralateral ear.
Don't forget!
An assessment by an audioprosthetist is required to determine which hearing aid suits the patient's needs.
