I recently had the opportunity to learn about a new bone conduction hearing aid system that doesn’t require surgery or the use of a soft headband, from the company MED-EL. MED-EL is well known for cochlear implants, and also their bone bridge, which is a bone conduction implantable system. Their new device, ADHEAR, is a clever play on words because it actually adheres a device behind your ear using an adhesive pad.
Before we talk about this option, it’s really important to understand how we hear. First, sound enters your outer ear through the ear canal and vibrates your ear drum. This vibration is transferred through your middle ear by the three middle ear bones. This vibration then enters the inner ear which contains your cochlea. Inside of your cochlea you have a number of structures, including three fluid-filled chambers, a basilar membrane, outer hair cells, and inner hair cells. The cochlea converts this vibration into an electrical impulse with the help of the outer and inner hair cells. This signal is then sent up the auditory nerve to the brain where the auditory cortex can interpret the sound, causing you to hear.
Let’s talk a little bit about how bone conduction works. When you have a conductive hearing loss, the vibration of sound can’t make it all the way from your outer ear, through your middle ear, to your inner ear which is your cochlea, otherwise known as your hearing organ. And when sound doesn’t make it to your hearing organ, it doesn’t even matter if you have a normally functioning inner ear. It will not matter if the sound can’t make it there.
However, the good news is that the cochlea, being made of bone, can actually accept the vibration when you vibrate the skull directly. This vibration will transfer all the way from the skull through to the inner ear and will stimulate hearing, regardless if you have any kind of an issue with your outer ear or your middle ear. This is why a bone conduction hearing aid can actually bypass conductive hearing loss. Not only does the ADHEAR Bone Conduction System work for conductive hearing loss, it will also work for a case of single-sided deafness, as long as your opposite ear has normal bone conduction scores.
Now, we’ll get into the details of the ADHEAR Bone Conduction System. First, let’s talk about the adhesive pad. The adhesive pad is extremely sticky. In fact, once you get it into place it should not budge at all. I have been wearing an adhesive pad for a week and it has not moved one bit. It just attaches on that mastoid bone behind whichever ear you want to use it on. You can use the same type of pad for your right ear and for your left ear. They’re designed to last three to five days but like I said, I’ve been wearing one for a week, mainly because I want to see if it causes any kind of irritation on my mastoid bone.
I typically have allergic reactions to certain types of athletic tape, so I wanted to see if the type of glue that they used on this actually caused an irritation on my mastoid bone. It feels really good to me, it hasn’t been bothering me the entire time that I’ve had it on, and it hasn’t caused any irritation. I was able to wear it for a full seven days. I didn’t even remember that I had it on unless someone mentioned it to me and asked me what it was. I work out and shower every day – and it never got in the way nor did sweat cause any issues with it losing its stickiness.
It comes in two different colors. I wore the darker color, but it does come in a lighter skin tone color than that (which probably would have been better for my Norwegian skin tone!).
Next, let’s talk about the sound processor. Basically, the sound processor attaches to a little raised bump on the sticky pad. The little bump looks like a post that you would normally have implanted into your skull if you went with the traditional bone conducted hearing aid.
Just like the pad, the actual bone conduction hearing aid will work on either ear, and it does come in several different colors. I had the opportunity to wear it for a little while, and it was actually really comfortable. It’s very lightweight, so you can hardly tell that you’re wearing anything. I shook my head around a bunch to see if it would fly off, and it didn’t.
The ADHEAR system uses a size 13 battery which will get you about two weeks’ worth of battery life, and it also has onboard controls to control volume and to adjust programs. It is FM compatible, which is terrific. It has the ability to communicate with other electronic devices; however, it will not directly stream from another Bluetooth device, so you have to directly input audio into the device. Of course, you have to be able to tether the device to those other electronic devices with a direct audio input.
Third, let’s talk about how well it works. The reason that MED-EL can get away with actually just sticking it to your mastoid bone rather than actually putting an implantable device in your skull is because that sticky pad is such a low mass that they don’t have to create as much vibration or as much power to transfer that sound through your skull. Clinical trials by MED-EL indicated that their participants using the ADHEAR system were achieving similar results as individuals who were using a headband. They were also achieving higher rates of satisfaction from the users, because using a soft headband is uncomfortable. If you don’t believe me, go wear one for a full day and let me know what you think.
The product is suitable for both adults and children. When I was able to demo the device, I could tell that it was giving me similar benefit to any other type of bone conduction device that I had demoed.
Let’s talk about potential drawbacks of this technology. First, you have to have normal bone conduction scores between 500 hertz and 4000 hertz, which means 25 decibels or better. This also means that it is not intended for mixed hearing losses. It is specifically designed for conductive hearing losses and cases of single-sided deafness when your bone conduction scores on the opposite ear are within the normal range (which again, are better than 25 dB thresholds). I could also see how maybe wearing glasses would cause a problem if it actually made contact with the bone conduction device behind your ear, but you could change your glasses.
It isn’t directly Bluetooth-compatible with a smartphone, which would have been a really nice feature. However, if that means that they would have had to make the device even larger, it’s probably a good idea that they didn’t.
Overall, the ADHEAR Bone Conduction System gives individuals with a unilateral or bilateral conductive hearing loss, or a single-sided deafness with normal bone conduction scores on the contralateral ear, an option to treat their hearing loss without going through surgery.
Med-EL is typically known for their Cochlear Implants and Middle Ear Implants. However, they just received thier FDA 510 (k) clearance which basically means it can be sold in the United States. Previously, the device was only available outside the US. The Med-EL ADHEAR Bone Conduction Hearing Aid System, works by adhering an abutment pad behind the ear on the hairless mastoid bone. Then, you attach the Sound Processor which provides bone conducted sound through the skull, into the Cochlea (hearing organ).
This vibration can bypass the traditional route of sound from the Outer ear, through the Middle ear, to the inner ear (cochlea). This allows someone with a Conductive Hearing Loss, or Single Sided Deafness, to bypass the hearing loss and stimulate the Cochlea with sound.
The ADHEAR has:
1. Adhesive Pad - This pad is very hypo-allergenic and stays in place for a week. Med-EL only claims 3-5 days, but I wore the pad for 7 days without issues.
2. Sound Processor - The processor is lightweight and comes in 3 different colors. It can work behind either ear seamlessly and snaps onto the Adhesive Pad. It uses a size 13 hearing aid battery, and has on-board controls for program and volume changes. It also is FM compatible and can be connected with other electronic devices with a cable.
Med-EL indicated that in clinical trials, they achieved similar results to a softband method of wearing a Bone Conduction Hearing Aid. The also indicated increased comfort of wearing the ADHEAR vs. a headband which led to higher satisfaction rates.Unfortunately, the ADHEAR only works for bone conduction thresholds that are better than 25 dB between 500 Hz and 4 kHz. The processor may get in the way of glasses, and it isn't Bluetooth compatible.