There are lots of different types of hearing losses, and lots of different hearing loss solutions. In the past we’ve talked about three of these solutions: cochlear implants, middle ear implants, and bone conduction implants. But do you know the fourth?
It’s Electric Acoustic Stimulation, or EAS. EAS is a special combination of two different hearing loss solutions designed for one very special type of hearing loss called high frequency hearing loss.
What Is High Frequency Hearing Loss?
As we showed in our post about how the cochlea hears sounds, high-frequency sounds are perceived in the bottom of the cochlea and low-frequency sounds are in the top. Because of this, it’s common for hearing loss to happen in the high-frequencies before it happens in the low frequencies.
When this occurs, and the cochlea is still able to understand some low-frequency sounds but no high-frequency sounds, the hearing loss is called “high frequency hearing loss”. This means that someone with high frequency hearing loss will be able to hear sounds like the roll of thunder, but will have difficulty hearing with sounds like the letters F, S, or K, and female voices. There are lots of different reasons why high frequency hearing loss occurs, including exposure to noise, ageing, or genetics.
EAS: Two Solutions For Two Hearing Losses
An ideal treatment for high frequency hearing loss is Electric Acoustic Stimulation, and by looking at its name we can see what makes it such a unique hearing implant. It’s the only type of hearing implant that combines both electric stimulation, which is sending electrical pulses directly to the nerve cells in the inner ear like a cochlear implant does, and acoustic amplification, like a hearing aid. This combination of stimulation is ideal for someone with high frequency hearing loss because it helps to reproduce the high-frequency sounds with electric stimulation, while using acoustic amplification to take care of the low-frequency residual hearing.
The electric stimulation is necessary to reproduce the high-frequency sounds because it can stimulate the cochlea even when no hair cells are present. It’s done with a cochlear implant and an electrode array designed specifically for high-frequency hearing loss.
But, because some hair cells in the low-frequency region still work (called “residual hearing”), the goal is to take full advantage of each and every one of these remaining hair cells. This is done with a solution that’s much different from a CI, and very straightforward: turning up the volume. Like a hearing aid, the EAS system sends amplified sounds to the cochlea along the ear’s natural hearing path.
This way, both the high-frequency and low-frequency hearing losses each get unique and targeted treatment to provide the best possible hearing.
If you’re more of a visual person , here’s a quick video that shows how the electric and acoustic stimulation combines in the ear:
Might I Have High-Frequency Hearing Loss?
Here are a few sample questions that you can ask yourself (or a loved one) to get information about your hearing. You can also find out more about what it’s like to have high-frequency hearing loss by visiting our Hearing Loss Stories.
- Do you have trouble following conversations when multiple people speak at one time?
- Do you have difficulty understanding when using the telephone?
- Does speech seem muffled?
- Do you have difficulties hearing door bells or birds singing?
- Can you hear male voices, but have difficulties hearing female voices?
If you said “yes” to any of these questions you might have high frequency hearing loss, and it would be a good idea to get in touch with a hearing professional for a complete hearing test and medical diagnosis.
EAS has been the ideal solution for high frequency hearing loss for the last 15 years. The first experiments into combining electric and acoustic stimulation were started in 19991. Since then, EAS has been developed and refined into a powerful system that gives hearing and listening scores of up to 50 percentage points higher than using hearing aids alone.
Visit the MED-EL website to learn more about solutions to treat high-frequency hearing loss.
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- Von Ilberg et al. Electric-acoustic stimulation of the auditory system. ORL, 1999; 61: 334-340.