Contra Lateral Routing of Signal (CROS) is a hearing aid technology for people with unilateral hearing. The technology allows two implementations: CROS and BiCROS.
Using this technology, a hearing aid-like device on the user’s poorer ear uses its microphone to pick up sound and sends it to another instrument at the better ear. The sound is then inserted into the better ear.
The CROS implementation is for a user who has relatively normal hearing in the better ear and has hearing that can’t be aided on the poor ear. The receiving BTE device on the poorer ear transmits the sound to a device in the better ear. The user hears the amplified sound from the poor ear in the better ear. The user hears the sound from the better ear naturally in their better ear, without amplification.
The BiCROS implementation is for a user with little or no hearing on one side and with some hearing loss in their better ear. It works just like the CROS implemenation, except that the device in the better ear is actually a fully capable hearing aid for hearing sounds from the better side that is also capable of receiving the sound transmitted from the CROS aid on the other side.
Transmission in a CROS or BiCROS configuration can be via wire around the back of the neck or wirelessly via radio.