CROS and BiCROS hearing aids

CROS (Contralateral Routing of Signals) aids are suitable for children with unilateral (single-sided) deafness where one ear has typical hearing and the other ear has little or no hearing. This system picks up sounds from the side with little or no hearing and sends it to the hearing ear. 

A BiCROS (Bilateral Contralateral Routing of Signals) uses the same principle as a CROS system, but is designed for children with asymmetrical deafness, where one ear hears substantially 'better' than the other.

More about other types of hearing aids.

How it works

CROS and BiCROS hearing aids look similar to conventional behind-the-ear hearing aids. For both systems, the user wears a receiver on their deaf ear (or the ear with more hearing loss), which wirelessly transmits sound to a hearing aid worn on the ear with better hearing. For BiCROS aids, the hearing aid will also amplify sound in the better ear, similar to how a conventional hearing aid works. 

In both systems, the sound is transmitted wirelessly (often via Bluetooth), helping the user hear more clearly from both sides.

Who can use it

• CROS hearing aids may be suitable for people with severe or profound deafness in one ear and typical hearing in the other.
• BiCROS hearing aids may be suitable for people with asymmetrical deafness, where one ear has significantly better hearing than the other (for example, mild deafness in one ear but profound deafness in the other). 

CROS and BiCROS hearing aids are generally not recommended for babies and young children due to safety concerns. They are designed for adults and often lack tamper-proof battery doors and have removable parts that could present a choking hazard. Additionally, there is limited evidence supporting their effectiveness for young children with unilateral or asymmetrical deafness. 

Therefore, CROS and BiCROS aids are usually only considered for older children and teenagers. For young children, other hearing aid options, such as bone conduction hearing aids, are typically considered first. 

An audiologist can help determine the most appropriate hearing aid based on a child’s specific needs. 

How sound is perceived

There is some limited research suggesting CROS and BiCROS hearing aids can improve speech understanding, sound localisation and hearing in noisy environments for children with unilateral hearing loss. Even though sounds only enter one ear, many children’s brains will adapt over time and learn to recognize the direction sounds are coming from. 

Hearing aids can give deaf children greater access to speech sounds, supporting their spoken language development. However, hearing aids do not restore typical hearing. A deaf child wearing hearing aids will not be able to hear in the same way as a hearing child. They may still struggle to hear if the person speaking is not facing them, is too far away or if there is background noise.

Models and brands

Most manufacturers have CROS and BiCROS aids that are compatible with their other range of hearing aids. Common manufacturers include Phonak and Oticon.

These brands offer a range of colours and styles. 

Availability of different brands on the NHS depends on where you live and your local department's arrangements. Your audiologist will recommend the best option out of what is available locally.

There's no evidence that one model is better than another. The most important thing is that the hearing aid is programmed to meet the child or young person's specific needs.