CROS and Bi-CROS Hearing Aids: : What they are and who should wear them


Many people out there have Unilateral Hearing Loss {link to unilateral HL blog}, meaning that they have hearing loss just in one ear.  If the loss in the poorer ear is severe or profound in nature and makes the ear “unaidable” (meaning that a hearing aid cannot help that particular ear), or if there is no residual hearing, the person may not be a candidate for a traditional hearing aid.  In this case, the hearing healthcare professional may recommend a CROS or BiCROS hearing aid system.

CROS is an acronym meaning “Contralateral Routing of Signals” and BiCROS is an acronym meaning “Bilateral Contralateral Routing of Signals”.  They are similar but different.  A CROS system is recommended when the wearer has normal hearing in his or her better ear.  A BiCROS system is recommended when the wearer has a mild to severe hearing loss in his or her better ear.  See the diagram below:






Both CROS and BiCROS systems work by wearing a transmitter that looks like a hearing aid on the poorer ear, and a receiver hearing instrument on the better ear.  The transmitter on the poor ear picks up and sends sound to the better ear.  If the better ear also has hearing loss, that sound is amplified to an appropriate level so that sounds will be audible.

Why would people choose a CROS or BiCROS system?

  • They are missing important information from their poor ear; this could be conversations, environmental sounds, traffic sounds, and so forth
  • They have difficulty localizing sounds and telling the direction from which they’re coming
  • They have to turn their head frequently so their better ear is toward the sound or what they’re trying to hear
  • They feel unbalanced wearing just one instrument on the better ear

CROS and BiCROS aids used to be hard wired, meaning that a wire literally ran from one ear to the other.  With the improvements in technology, CROS and BiCROS systems are now largely wireless, and are available in both Behind-the-Ear and In-the-Ear styles.

← How CROS and BiCROS aids used to look


How CROS and BiCROS aids look now

As you can see, CROS and BiCROS systems look just like regular hearing aids.  Hearing Revolution offers the Audifon CROS and BiCROS systems.  To learn more about this product, click here:

The common goal of CROS and BiCROS fittings is to provide audibility and awareness of signals from the unaidable side of the head to the better ear.  While this is a good thing, it is worth mentioning that the amount of benefit from these systems does decrease when presented with background noise.  It can be very difficult for wearers to understand when in a situation with much ambient noise.  Wearers may also feel that the hearing aid system sounds distorted or unnatural (this can, in part, have to do with the type and nature of the hearing loss in the poorer ear) and reject the instruments.  The success of CROS and BiCROS systems is variable and depends on the wearer, his or her motivation, and his or her expectations.

CROS and BiCROS aids are not for everyone, but are an extremely viable option in the case of unilateral hearing loss with an un-aidable ear.  Talk to your hearing healthcare professional about it today!

Until next time,

Dr. Kristin