People with single-sided deafness or one ear that is not able to understand speech clearly are at a significant disadvantage when attempting to understand speech and other sounds. This type of hearing loss is called a unilateral hearing loss. This problem is increased when there is noise in the room while the desired sound is occurring. They have difficulty judging the distance a sound is from them and the location of the sound. This discrepancy in how the two ears hear sound interferes with how the brain processes sound.
How CROS Hearing Aids Work
The hearing aids used by people with only one working ear are called the CROS. The acronym stands for contralateral routing of signal (CROS). With CROS hearing aids, the person wears a hearing aid on each ear. A microphone picks up the sound from the side of the head with the extremely poor hearing and transfers it directly to the receiver in the hearing aid on the other side in the better ear. This helps a person hear in real time from both sides of their head. With practice, many people are able to relearn how to determine the location of sound that they hear while wearing these aids.
Custmizing BiCROS Hearing Aids
Some people have one ear that does not work at all and the other ear is not hearing within normal limits. In that case, we order BiCROS (bilateral routing of signal) hearing aids. BiCROS aids house the transmitter in the hearing aid of the poor hearing ear and sends a signal to the better hearing ear. But the hearing in the better ear needs to be increased so this system is able to change the sound to the better ear after picking it up. The changes are set in the computer of the hearing aid by the audiologist based on the hearing test and the desires of the person. The system is extremely flexible; you can have the CROS side louder or softer, depending on the needs of the situation.
Life-Enhancing Rechargeable Feature
One of the most common complaints of using CROS or BiCROS hearing aids is length of battery life. The CROS hearing aid is constantly sending a signal out to the other aid, causing the battery to drain in two to three days! The hearing aid on the better hearing side usually lasts a few days longer, but this means you change batteries in the hearing aids at different times and need to have spare batteries with you at all times. This can be frustrating and even cause people not to wear their CROS aids because they are not able to depend on the power source.
Now, we have rechargeable CROS and BiCROS hearing aids that last 30+ hours at a time! Most of us do not stay awake 30 hours to drain the battery fully. Each night before you go to bed, you place the hearing aids in the charging unit and when you wake up, the hearing aids are fully charged and ready to go for another 30+ hours. There is a battery pack to store energy in case the power goes out at the house or you are going camping. The battery pack stores enough energy for 10 charges without being plugged into the wall.
Typical CROS/BiCROS Hearing Aid Fittings
A typical fitting of this technology is for the people who lost hearing in one ear by a virus, head injury, surgery or who were born with the hearing difference. I always recommend to my patients that it is a great idea to try out the CROS aids just to see how you do.
CROS hearing aids may be worn by a person who has normal hearing but is not able to understand speech in one ear. The brain is not able to take sound and convert it into usable sound. That person is stressed when in a group of people talking because the sound coming in the “challenged” ear picks up static and actually causes confusion. With the CROS aid, the sound from the side of the head that does not understand is transmitted to the other ear that understands well.
Which Hearing Aids Will I Need?
To determine what type of hearing aid is needed, you will first have a diagnostic hearing test to determine the type and degree of hearing loss and word clarity you have in both ears. Your audiologist will discuss options, which you will be able to try at home to see which aids offer you the best quality of life improvement. QCBN
By Karon Lynn, Au.D.
Trinity Hearing Center is located at 1330 N. Rim Dr., Suite B in Flagstaff. For more information, visit the website at TrinityHearing.net. Karon Lynn is a doctor of audiology with 30 years of experience working with hearing impaired individuals. Dr. Lynn may be reached at 928-522-0500 or at firstname.lastname@example.org.