What Does It Mean to Have “Normal” Hearing?

We talk about healthy hearing sometimes without really understanding what that means. Is it the ability to hear someone or is it protecting your hearing from loud sounds, infections, and head impact? Well, the answer lies amid these and many other factors. Many times, instead of healthy hearing what we mean is normal hearing – or the baseline we are basing a hearing loss off of. 

How is “Normal” Hearing Measured?

Often when someone has to ask people to repeat themselves frequently or struggles to hear the phone or TV at a normal level, they will suspect they have a hearing loss. Hearing loss is measured during a hearing test and printed in the form of a chart called an audiogram. The pure-tone audiometry is a behavioral test used to measure hearing sensitivity by measuring the peripheral and central auditory systems. Pure-tone thresholds (PTTs) indicate the softest sound audible to an individual at least 50% of the time. By definition, “normal” hearing is the absence of hearing loss.   

Understanding Audiometric Zero

To understand “normal” hearing, the first thing to understand is the “audiometric zero”. Audiometric zero symbolizes the quietest tone that is detectable to the human ear when no hearing impairment is present. First established based on thousands of tests at the 1933 World’s Fair, researchers were able to get an average reading of the lowest threshold that people could hear when a hearing loss was not present. This is the basis for what is considered “normal” hearing, even today.

How We Measure Sound

Sounds are vibrations that create sound waves. The number of sound vibrations emitted per second is formulated as frequency and measured in hertz (Hz).  The lower the frequency, the fewer vibrations per second and the lower the pitch of the sound. On the other side; the higher the frequency, the more vibrations per second, and the higher the pitch is recorded. The intensity or loudness is measured in decibels (dB). When normal hearing loss is measured it lies between a range of 0 dBHL (Decibel Hearing Level), to 20 dBHL.  In an audiogram, if a person can hear sound within this threshold of 0-20 dBHL then there is no hearing loss present. Any sound which cannot be detected is considered a hearing loss, though this is also categorized into different degrees.

Mild to Profound

Hearing loss is categorized into different degrees of hearing loss. When we are younger most people tend to have better hearing, which declines as we age due to several factors such as exposure to noise, impact to the head, exposure to chemicals, ear infections, or just natural aging in the inner ear. A young person with normal hearing averages a hearing frequency range of about 20 to 20,000Hz. It is common with age that the upper frequencies are the first to go. By middle age, the average frequency detected averages around 14,000Hz. Even so, hearing loss can occur at any age and is measured within these ranges.

• Normal Hearing:  –10dB to 25dB
• Mild Hearing Loss: 26dB to 40dB
• Moderate Hearing Loss: 41dB to 55dB
• Moderately Severe Hearing Loss: 56dB to 70dB
• Severe Hearing Loss: 71dB to 90dB
• Profound Hearing Loss: 91dB+

Assessing Hearing Loss 

The World Health Organization (WHO) estimates that currently, more than 1.5 billion people (nearly 20% of the global population) live with hearing loss. Approximately 430 million of them have disabling hearing loss and they project that this number could double by 2050, to over 700 million globally. 

WHO believes that the key to slowing down the steady growth in numbers of people affected by hearing loss is proper education around hearing safety and limits of decibels globally in technology. Meanwhile many continue to underestimate its serious impact on communication, emotional health, mobility, and even cognitive functioning. Even a mild hearing loss has been found to cause people to score lower on cognitive function tests as more brainpower is devoted to deciphering conversation and away from other processes. 

Schedule a Hearing Test Today

It is important to test for hearing loss regularly, even if you don’t suspect that you have an issue. Often hearing loss goes undetected for years because people don’t even know they have an issue. Still, ignorance of a hearing loss doesn’t mean it’s not already taking a toll on your mental and physical health. Start taking your hearing more seriously today and schedule a hearing test.