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What is CROS?

 In CROS, Hearing Aids, Hearing Technology

CROS stands for contralateral routing of signal.  It is used to treat someone who is deaf in just one ear.

A CROS device has a hearing aid, which is worn on the good ear, and a transmitter, which is worn on the bad ear. Although the transmitter may look like a hearing aid, it actually picks up sound entering the bad ear and sends it to the hearing aid on the good ear. The hearing aid then sends the received sound into your good ear.

In some cases where the good ear has hearing loss, it can also amplify sound.  In this scenario, the device is called BiCROS.

Here is a diagram to visualize how CROS and BiCROS work.

CROS has been around since 1964. At that time, it needed a wire to connect one side to the other. This obviously was inconvenient and unattractive. Needless to say, the device was not very popular.

In 1975, Telex introduced a wireless option. Wireless solved the bulky and ugly look of the old CROS, but it too had its problems. Users often reported a bad connection with wireless. Audiologists and patients disliked it because of how unreliable it was.

Since 2010, the wireless communication between devices has improved greatly, thus, current CROS technology is very reliable. But, like all wireless communications, it can run into interference. While walking through security systems at stores, standing near microwaves, or flipping light switches, some users reported problems. Yet, most CROS users do not experience these. Even so, because of the ineffectiveness older devices, many professionals are hesitant to work with it again.

For more brand specific information on CROS and BiCROS you can click on the manufacturer’s sites here: Widex and Phonak.

Patients that use CROS are able to hear on their bad side, useful in social situations. There are some drawbacks though. It cannot restore localization of sound. What does localization mean?  It is our ability to know which direction a sound comes from. Localization requires two hearing ears and because CROS users have only one hearing ear, it cannot improve localization.

If you or a loved one would like to learn more about CROS technology or hearing loss, please schedule an appointment at Arizona Hearing Center by phone at 602.313.1243, or by email at

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