Many people can hear very little in one ear, to the point that even a hearing aid will not help. If you can only hear in one of your ears, the side of your head actually prevents your good ear from hearing things on that side of your body. In some environments, this phenomenon is not that big of a deal, but in bars, restaurants, or other crowded social gatherings you can miss the majority of vocal communication.
CROS hearing aids help to fight this type of hearing loss. With CROS hearing aids, even though you can only hear out of one ear, you wear hearing aids in both. Sound is detected by both hearing aids, but the sound detected by the hearing aid in your “bad ear” is transmitted directly to your “good ear.” You are then hearing all sounds and all frequencies heard on both sides of your head in your one good ear. You are a candidate for CROS hearing aids if you have severe hearing loss in one ear or cannot hear in one ear at all, and approximately 60,000 people in the U.S. develop this problem every year. The following is a description of CROS hearing aids including a review of how they work and how they are different than other hearing devices.
It is important to note that there is another form of this type of hearing aid called a BiCROS hearing aid. The same principle applies, but BiCROS is for people who have hearing loss in both ears with one ear too severe to be helped enough by regular hearing aids.
What Is Directional Hearing?
Directional hearing is what allows you to identify where a sound originated. People do not consciously participate in directional hearing, but it does greatly affect your life. Directional hearing is determined primarily by two factors:
- The shape of your ears. The way that your ears are shaped cause them to act as a forward-facing funnel essentially giving preference to sounds in front of you and making those sounds louder than the ones coming from behind.
- Binaural Hearing. Having two ears allows you to more effectively localize sounds as your brain effectively “triangulates” the origin of the sound you hear by comparing how each ear perceives the sound.
While it is important to have the ability to localize sound and have a general idea of the direction from which the sound comes, it is not the most important function of directional hearing. Directional hearing is actually a key factor in our ability to perceive sounds and filter out those that are most important to us. This is particularly important in your ability to carry on conversations with people and even more important when doing so in environments with a lot of background noise. Your ears are trained to localize and hone in on the voice of a friend or television program precisely because you can localize where the sound is coming from.
What Are CROS Hearing Aids?
The term “CROS” is actually an acronym that stands for “Contralateral Routing of Signals.” As it was described above, CROS hearing aids are the solution for people who have profound hearing loss in one ear and rely on their good ear for all of their hearing.
- What Are CROS Hearing Aids Used For?
It may seem logical that if you cannot hear out of one of your ears you simply need to rely on the other ear to get you through. However, there is something called the “head-shadow effect” that makes operating with only one “good ear” virtually impossible. If a sound originates from the side of your body with the “bad ear,” your head blocks that sound from reaching your good ear. This phenomenon tends to affect consonants and high-frequency sounds at a greater rate than others which makes it even more difficult to understand speech, but if your hearing loss is profound enough or complete then it affects every aspect of your hearing. You would have to turn your head to the side where sound is occurring constantly to be able to hear any sound on that side of your body, and that would be an exercise in futility. CROS hearing aids were created specifically to fight against this effect and to offer you the ability to hear 360-degrees of sound in your one good ear regardless of which side of you body it is.
- What Are The Advantages?
The main advantage of CROS hearing aids is that it gives you the ability to localize the origin of the sound you hear. It gives you access to all of the sound in your environment, but then it allows your hearing aids to work together to provide the directional hearing that you would miss if you could only hear out of one ear. The benefits of directional hearing are described above. The following is a list of some of the other advantages of CROS hearing aids:
- Takes away the “head-shadow effect.”
- Allows you to triangulate sound so that you know its origin.
- Have the option of BiCROS hearing aids if both ears suffer from hearing loss.
- Can come in different strengths so that you can still use some natural hearing if it is still available.
- Better speech clarity and understanding.
- Tinnitus relief options.
How is CROS different from other hearing aids?
Traditional hearing aids process sound and then send it directly into the ear on which they are sitting. The primary purpose of a traditional hearing aid is to make sounds louder and more usable so that a person with hearing loss can listen, communicate, and participate in everyday life. The hearing aid receives sounds, amplifies and processes those sounds, and then sends those sounds directly to your ear.
CROS hearing aids, while they do process sound, do not do so simply to send the sound to the ear it is sitting on. Instead, a CROS hearing aid sits on the wearer’s “bad ear” and is simply a microphone and a transmitter with no amplifier or speaker. The microphone picks up the noise that the ear would normally hear and immediately transmits that sound to the accompanying hearing aid in the wearer’s good ear. When wearing a CROS hearing aid, all of the sound will only be heard in one ear. While this helps, it does not fully replace your directionality and it does usually take quite a bit of getting used to. Most people who wear CROS hearing aids do so later in life which makes the transition from hearing with two ears to one ear that much more difficult.
Who is a candidate for CROS and BiCROS?
CROS hearing aids are ideal for people with single-sided deafness. Most people who are a candidate for CROS hearing aids have relatively normal hearing in their other ear while their “bad ear” cannot be helped by standard hearing aids. The vast majority of people who experience single-sided deafness develop it rather than being born with it which causes certain issues as well. Some of the causes of single-sided deafness include:
- Viral infection
- Trauma to the head
- Shortage of blood to the auditory pathway
- An acoustic neuroma: a benign tumor on the nerve that connects the ear to the brain.
- Meniere’s Disease: fluid buildup in part of the inner ear.
Are CROS Hearing Aids More Expensive Than Normal Hearing Aids?
The short answer is that CROS hearing aids are similar in price to normal hearing aids. Most of the major brands sell some form of CROS hearing aids and often in the same family and with similar features to their normal hearing aid lines. While they are a specialty product, much of the technology is either lower or similar to normal hearing aids and that reflects in the price similarity. For a good pair of CROS hearing aids you can expect to pay anywhere from $1,500 to $5,000 or more. The price also depends on the level of service you receive from an audiologist both before and after the purchase. CROS hearing aids can be complicated devices and it is vital that you get the settings correct so that you enjoy all of the benefits they have to offer. Having an audiologist walk with you through the process is highly advised.