Diplacusis: Understanding double hearing

What is double hearing?

Diplacusis is derived from the Greek words “diplous” (double) and “akousis” (hearing). It is a hearing condition that can cause a person to hear sound in one ear at a different time or pitch than the other ear.  Also known as interaural pitch difference (IPD), diplacusis can be caused by an obstruction within the ear canal (such as an object or tumor) or excess ear wax. Severe infections may also create inflammation that damages the inner ear. Some cases of diplacusis occur in people with Meniere’s disease.

Diplacusis is triggered by damage to the tiny hairs in the inner ear that send sound information to the auditory nerve. This causes one ear to hear differently than the other ear, creating this “double hearing” experience. Diplacusis can occur suddenly or develop over time.

On its own, diplacusis can create challenges in getting through day-to-day life. To make matters more difficult, people who experience diplacusis sometimes also develop tinnitus. Once you know which type of diplacusis you have, there are options for treatment.

Types of Diplacusis

Knowing what the symptoms of hearing loss are of each type of diplacusis can help you figure out which type you get help with treatment. You can tell which type of diplacusis you have by looking at how hearing works: when both ears are functioning at the same level, timing, pace and pitch, we hear perfectly. When they are working differently, that’s when we experience distortions that prevent us from hearing sound as it really is. For example Diplacusis Dysharmonica and Diplacusis Binauralis are related to pitch, Diplacusis Echoica is related to timing, and Diplacusis Monauralis is related to multiplying sounds.

Of the four documented types of Diplacusis, the two main types of Diplacusis are Dysharmonica and Echoica. Dysharmonica is by far the most common form of diplacusis, which is when a person struggles with hearing different pitches of sound. But if a person experiences an echoing effect, this indicates the Echoica type of diplacusis resulting from the ears hearing at different speeds.

Diplacusis Dysharmonica

Diplacusis Dysharmonica is when each ear hears sounds in different pitches. What does this sound like? It’s often described as “hearing in stereo.” One ear is hearing sound in its correct tone, while the other ear may be hearing the same sound in either a higher or lower pitch. While traditionally our brain hears pitch as one sound, this phenomenon creates two separate sounds. This makes each ear’s combined effort of discerning different pitches hard to do. It becomes almost impossible to know which is the true tone.

Diplacusis Echoica

This type of diplacusis is a timing issue. It happens when one ear hears sounds more quickly than the other ear, creating an “echo” effect. If you have this form of diplacusis, you may experience a sound repeating in the same ear: the first sound followed by an echo of that sound. This makes it very hard to understand someone speaking.

Diplacusis Monauralis

With Diplacusis Monauralis (monaural diplacusis), one ear hears a single tone as two different sounds. When this happens, the sound seems to have different pitches or be distorted. As with Diplacusis Echoica, this can also make it difficult to understand what someone is saying. However, rather than multiple sounds occurring at different times, Diplacusis Monauralis makes it seem like multiple sounds are layered on top of one another at the same time.

Diplacusis Binauralis

Binaural diplacusis, also referred to as “binaural harmonic diplacusis,” occurs when one ear perceives the same tone is perceived as having a different pitch depending on whether it is heard by the left ear or the right ear. This type of diplacusis tends to be more common in people who are hearing impaired or who have asymmetric hearing loss.

Symptoms of Diplacusis

If you have Diplacusis, you may notice symptoms of hearing loss begin right after being exposed to loud noises, having an infection, getting a blockage in the ear, injury, or trauma. It may also begin when starting certain medications. It can happen over time as well, since hearing loss can be a slow-developing problem. You may notice hearing loss in only one ear versus both ears, or you may have uneven hearing loss. In addition to this double hearing, people with diplacusis may also find they have tinnitus, or ringing or buzzing in the ear as well.

You may have an obstruction in the ear due to a tumor, clogged sinuses, excess earwax, or from a sinus infection. Luckily, if Diplacusis is present due to an obstruction, hearing may return to normal once the infection heals or the obstruction is removed. Otherwise, treatment for Diplacusis will depend on the underlying cause. When the condition is permanent, listening devices such as cochlear implants and hearing aids can help tremendously.

Causes of Diplacusis

Causes of hearing loss that trigger diplacusis can include:

• Exposure to loud noises. One type of hearing loss is noise-induced hearing loss (NIHS), which happens when you’re exposed to extremely loud noises without proper hearing protection. This can traumatize the inner ear, causing temporary or permanent damage.
• Hearing loss related to aging. Our ability to hear as well as we once did decreases as we age. Some age-related hearing loss is to be expected, but some people experience more severe hearing loss than others. Some also experience it sooner than others, and can have reduced hearing abilities as early as their forties.
• Head trauma. Any blunt force to the head and significantly impact the fragile structures of the inner ear, causing hearing loss. A severe car accident causing an airbag release, a fall off a bike, a sports injury, or just a bump on the head resulting from clumsiness is enough to have an impact on hearing. If you have experienced any of these, it’s possible this could be the root cause of your diplacusis.
• Medications. While the exact reason isn’t clear, certain antibiotics, over-the-counter (OTC) pain relievers, opioids, erectile dysfunction medications, chemotherapy drugs and malaria medications can cause direct damage to structures in your inner ear, leading to diplacusis.
• Obstructions. If you are battling a severe infection resulting in inflammation and severe congestion in the ears, or if you have a buildup of excess earwax, this can cause damage that results in hearing loss. Eustachian tube dysfunction can sometimes cause this as well.

Diplacusis treatment options

The good news is that if your Diplacusis caused by a blockage, the condition can be cured or improved by removal of the obstruction or by clearing a severe infection. If it is caused by trauma or a sudden loud noise, it may be possible for the condition to improve over time as you heal. If it’s the side effect of a medication, stopping the use of that medication or finding an alternative could also solve your problem. Never stop a medication without first talking to your prescriber and your audiologist.

If your hearing loss is permanent, your Diplacusis may need to be treated with hearing aids or cochlear implants. Auditory rehabilitation or auditory training, which uses mental exercises to help your brain adapt to the new way it hears sound, is another option that can complement the use of hearing aids to help boost results.

One of the best things you can do first is to make an appointment with an audiologist to do a hearing test. This can help pinpoint your unique type of diplacusis, and figure out options that may support your condition the most. From there, your audiologist can explain different types hearing aids that would best fit your needs and lifestyle.