Diplacusis or "double hearing" explained

 

Diplacusis, also known as “double hearing” is a hearing disorder that causes each ear to perceive the same sound differently. In most cases, the pitch is perceived to be higher in the ear with poorer hearing. It can have a troubling impact on musicians and others who rely heavily on their discernment of pitch.

If you suspect you may be suffering from diplacusis, book a hearing test to get an official diagnosis and discuss your treatment options. A hearing professional can help determine the cause of your diplacusis with a full hearing assessment.

What causes diplacusis?

Diplacusis is commonly caused by 

• An ear infection
• Damage to the inner ear and/or 
• Head trauma. 

The exact mechanics behind double hearing are not fully understood. This unusual response to sound may be occurring in the inner ear or from neurons in the brain responding to a damaged inner ear.

Diplacusis has been observed in people with normal hearing, though it is more common and severe among those with hearing loss. Some researchers consider a pitch difference of less than one semitone to be normal.

And although diplacusis usually results in a higher pitch perception in the problem ear, some cases have a lower pitch perception.

Types of double hearing

Double hearing can occur in one or both ears, although it more commonly affects both.

If your double hearing is in one ear, it is known as diplacusis monauralis. Double hearing in both ears is known as diplacusis binauralis.

There are two main types of diplacusis binauralis: dysharmonica and echoica.

Diplacusis dysharmonica

Diplacusis dysharmonica is when one ear perceives sound at a different pitch from the other ear. 

Diplacusis echoica

Diplacusis dysharmonica is when one ear hears sound faster than another, creating an echo.

It is also possible to have a combination of both types.

Treatment options for diplacusis

Treatment for diplacusis depends on the type of hearing loss causing it. 

For example, diplacusis connected to age-related hearing or noise-induced hearing loss may be treatable with hearing aids.

Prevention tips

Diplacusis is rare, but you can reduce your risk by:

• Wearing earphones at a safe sound level to reduce your risk of noise-induced hearing loss,
• Wearing hearing protection when exposed to sounds above 85 decibels and
• Wearing head protection when recommended or required

Musicians, especially professional classical musicians have a higher risk of getting diplacusis. Those who already have hearing loss, especially asymmetrical hearing loss are also at risk.

How long does diplacusis last?

Diplacusis can be temporary or permanent, depending on what the cause is. If it is caused by age-related hearing loss, it will likely not go away.

If it is caused by an obstruction in the ear or an infection, it may go away once the obstruction is removed or the infection is treated.

Those with normal hearing can perceive pitch differences between their left and right ears, but the difference is usually smaller compared to those who have hearing loss. Some researchers consider a pitch difference of less than one semitone to be normal.

^Sources

^{- Healthy Hearing. https://www.healthyhearing.com/report/51055-Understanding-diplacusis}

^{- Canadian Audiologist. https://canadianaudiologist.ca/issue/volume-10-issue-4-2023/the-case-of-the-missing-c/}  

^{- International Journal of Environmental Research and Public Health. https://www.mdpi.com/1660-4601/15/10/2120} 

^{- PLOS ONE. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0159975}