High vs. Low-Frequency Hearing Loss

Curious about the two main classifications of hearing loss? What differentiates them from one another? How does each manifest?

In broad strokes, there are two major classifications of hearing loss, defined based on the type of sound you have trouble hearing. In order to adequately describe either of them, though, we'll need to start with a quick primer on how sound is measured. A given sound has two significant traits.

Volume, or amplitude, is relatively self-explanatory. The higher the peaks and the lower the valleys are in a sound wave, the louder that sound becomes. This is measured in decibels (dB). 

The human ear can safely listen to sounds of up to 70 dB without risk. Anything above that, and you may start to damage your ears. Sounds above 120 dB are known as catastrophic or traumatic noise, and hearing damage is almost guaranteed at this level.

Aside from being a contributor to hearing loss, amplitude doesn't have much more of a role here. 

Frequency, also known as pitch, is measured in Hertz (Hz). Whereas amplitude measures how large each soundwave is, frequency measures how closely-packed those waves are. The more tightly packed the waves become, the higher the sound's pitch. 

Someone with healthy ears and a standard range of hearing can generally discern sound ranging in frequency from 20Hz to 20000Hz. Anything below 20Hz is known as infrasound, which some scientists theorize may have a negative effect on one's health. Anything above 20,000Hz is ultrasound ― the diagnostic technique of the same name actually maps out parts of the human body via ultra-high frequency soundwaves. 

The Three Frequencies of Sound  

Because amplitude tends to be so variable, soundwaves are generally classified by frequency.

• Low-frequency sounds are 500Hz or lower. Examples include a pipe organ, a truck's horn, or a cat's purr. These sounds are perceived as deeper and lower. 

• High-frequency sounds are 2000Hz or higher. Given that the upper range of human hearing is around 20,000Hz, this classification is incredibly diverse. Examples include chirping birds, small bells or chimes, or the meowing of a hungry cat. 

• Medium-frequency sounds fall between 500Hz and 2000Hz. Most human speech falls into this category. 

With all that established, let's move to the real meat of the discussion ― hearing loss. 

What is High-Frequency Hearing Loss? 

High-frequency hearing loss refers to difficulty hearing sounds in the 2000-8000Hz range. It's the most common type of hearing loss by far, likely in part because the stereocilia that convert high-frequency sound to sound waves tend to be more delicate. It's incredibly common in both noise-related hearing loss and age-related hearing loss. 

It appears on an audiogram as a line gradually descending from left to right. 

Someone with high-frequency hearing loss may have trouble discerning consonants or hearing people with higher-pitched voices speak. Potential causes of high-frequency hearing loss are unsurprisingly quite diverse. They include, but certainly are not limited to: 

• An adverse reaction to medication

• Genetic factors

• Exposure to traumatic noise levels

• Ototoxic medication

• Underlying health conditions such as diabetes or heart disease

• Presbycusis (age-related hearing loss)  

   

What is Low-Frequency Hearing Loss? 

Low-frequency hearing loss is far less common than high-frequency hearing loss, and encompasses sounds below 2000Hz. Unlike high-frequency hearing loss, low-frequency hearing loss is generally caused by either illness or disease. Common causes include:

• Meniere's Disease

• Otosclerosis

• Ramsay Hunt Syndrome

• Secretory Otitis Media. 

• Genetics

• Severe illness in childhood

Low-frequency hearing loss is also known as reverse-slope hearing loss due to the shape its audiogram takes.

As you might expect, the symptoms of low-frequency hearing loss are in many ways the inverse of high-frequency hearing loss. Someone with this condition may find it easier to hear high-pitched sounds, particularly those which might otherwise be beyond our auditory range. 

The biggest challenge represented by low-frequency hearing loss is that it's more challenging to diagnose, often misdiagnosed as a symptom of another health issue if it's not ignored altogether. 

Pick Your Poison

Regardless of what type of hearing loss you're dealing with, treatment is generally the same. Get examined by a seasoned audiologist. You can also find some convenient online hearing test available to take. With any luck, by working together with a hearing professional, you can devise a treatment plan that fits you like a glove or figure out what is the latest hearing aid technology that can assist you. It helps ensure that whatever hearing impairment you may have, it doesn't need to bring down your quality of life.