THE AUDIOLOGIST’S BOOTH
by Michael Bergen. M.S., CCC-A
Question: Why do so few audiologists/hearing aid dispensers recommend bi-cross aids for those who have hearing in only one ear? In my area only one audiologist sells/fits them and many HOH people who could benefit have never heard of them.
Michael: CROS is an acronym that stands for “Contralateral Routing of Signal”. It is a special type of hearing aid that functions like a mini-PA system, collecting sound into a microphone placed on or in the poorer hearing ear (typically, an ear that does not obtain benefit from a more traditional hearing aid) . That microphone/transmitter then directs the sound to a receiver placed in the better-hearing ear. The CROS is typically used in the situation of unilateral hearing loss (i.e., one normal hearing ear and the other ear with severe hearing loss or poorer, and/or with little to no measureable word recognition ability). There are variations of the CROS, such as the BICROS, which not only brings sound to a better-hearing ear, but amplifies it to compensate for hearing loss in that better ear. A Multi-CROS is a further variation of the theme, allowing the user some flexibility to use the receiver as a stand-alone hearing aid. In all cases, the consistent theme is use in an ear that is generally thought to otherwise be “unaidable”.
The earliest CROS devices were hard-wired. One manufacturer held the rights for a number of years to a wireless CROS before leaving the hearing aid manufacturing business. In recent years, other companies have reintroduced the technology.
Obviously, I cannot speak for all dispensers, but the answer to the question may lie in the statistics. CROS and related devices have generally held a lower patient satisfaction rate than more traditional styles of amplification. While there may be a number of reasons for this, the fact that they are designed for unilateral hearing loss (with its inherent limitations) limits its place in the market, and the unique characteristics of this type of hearing loss may present a ceiling to the amount of benefit that can be achieved. Another reason is that while they do bring sound that is presented to the poorer ear, and direct it to the user’s better ear, they do not provide bilateral hearing ability.
One aspect of hearing ability that CROS hearing aids are designed to improve is the signal-to-noise ratio. Generally, people with unilateral hearing loss, having to rely on one ear, tend to do more poorly understanding speech in the presence of noise. This is further exacerbated when noise levels occur closer to the person’s good ear, and the desired speaker is on the listener’s “poor” side. To demonstrate this in a real-life situation, suppose a fictional patient, let’s call him John Morales, has a unilateral hearing loss in his right ear, the left ear being within normal limits. In face-to-face conditions, Mr. Morales may have little trouble hearing others, including his wife Susan. However, when he is driving a car he can have significant trouble hearing his wife in the passenger seat. The CROS hearing aid can provide improvement in this situation, as Mrs. Morales’ voice is directed into the transmitter sitting on the poor ear, and sent to her husband’s left ear, which does the actual hearing. If John finds that the benefit he obtains in these more isolated situations outweighs the fact that he does not perceive benefit in other situations, he would be more likely to keep this device. My belief is that some people reject the technology as it requires TWO physical components, and while many in this target population have a hearing loss only on one side, their perception is that the device is a bit unwieldy considering that benefit is limited to certain situations. Return rates for the device were historically high. The company that offered it as a sole provider for many years imposed a significant return fee, which may have served to hinder its progress, thus discouraging consumers and dispensers from ordering it.
Having said all of that, I was someone who opted to rarely consider this type of device in my early years in the profession. That was until I had two successes within a short time of each other. In one of those cases I saw a gentleman who had been to three dispensers in the past, not one of whom had recommended a CROS hearing aid. After fitting him, I’ll never forget how at our first follow-up appointment, both the man and his wife were in tears, the client informing me how he felt he’d “lost several years of his life” by not having been advised sooner about the CROS. Since that day, I’ve always been sure to educate those with unilateral hearing loss about the potential benefits of this technology. In short, it’s a limited population for whom this device is appropriate, but it has potential to provide benefit to those with unilateral hearing loss, and should always be presented as an option to those in this group.
Question: I have two questions. First, how should we maintain and care for our hearing aids so that they will last longer?
And second, what is the normal longevity of an earmold and how should we maintain and care for it? Thank you in advance.
Michael: Seeing as the number one reason for hearing aid disrepair is cerumen (ear wax) and other debris that infiltrates the receiver, the best action is proactive care of the device. Keeping all external ports clear of debris (whether visible to the eye or not) is often critical to long-term care. I recommend that a dry cloth be used to gently wipe the receiver port (the part that goes into the ear canal) daily, and that a soft brush (such as those packaged with a new device) be used occasionally to keep those parts clear. Debris generally becomes a problem when left untended. Microscopic particles can be transferred from the ear canal to the external surface of the hearing aid. If left in place, the next time the hearing aid is inserted, that microscopic debris may be pushed deeper into the device. The cumulative daily impact may eventually result in a plugged receiver tubing, may cause the receiver itself to become blocked or may directly impinge upon the deeper circuitry of the device. In all cases, sound will be affected. While some people produce enough debris for this process to occur within days, others may produce such a small amount for the process to take months or years to become affected.
In addition to keeping all ports (microphone and receiver) clear, it is helpful to take protective action and engage in safe habits such as being sure to keep your device safely away from pets or threats which may cause it to become crushed or accidentally thrown out (for example, I’ve had some patients engage the bad habit of keeping their hearing aids “protected” in a tissue when not in use. As you might imagine, this occasionally results in the device being accidentally tossed out with the trash). Keeping hearing aids away from water will generally help protect them and lengthen their usable life.
Earmold life varies by the style and material, and can range from six months to several years. Children, for example, have ears that continue to grow and therefore earmolds must be changed more frequently (to ensure fit). Additionally, someone who has a greater degree of hearing loss is more likely to go through earmolds more frequently, as a tight fit continues to be the best way to combat potential feedback for those (although today’s technology has improved significantly with regard to feedback control, it still does not compensate for a poorly fitting earmold on someone with severe or profound hearing loss. That being said, on the average an adult is likely to use his/her earmold comfortably on the order of 1-2 years.
Michael Bergen is the Director of Brooklyn College's Speech and Hearing Center and is on the faculty of the Doctor of Audiology (AuD) Program at the CUNY Graduate Center. Michael is a NYS licensed, ASHA certified audiologist. As Director, Michael oversees daily operations, supervising clinical sessions and teaching doctoral, masters and undergraduate students. He was recently honored with the "Distinquished Service Award 2008" by NYSSLHA and named Favorite Teacher" of the Dept. of Speech & Communication Arts & Sciences by Brooklyn College for 2007 and 2008.
Michael was elected NYSSLHA VP of Audiology 2006-07, 2008-09 and has chaired or served on committees at the university, local, state and national levels, including for NYSSLHA, ASHA, AAA, CAPCSD and the Metro Council.