In the world of hearing loss we refer often to the idea of normal hearing. The definition of normal is “conforming to a type, standard, or regular pattern. When referring to humans, we often like to celebrate our diversity, however the idea of normal hearing is used as a base line reference by audiologists to determine the degree and severity of an individual’s hearing impairment.
We refer to hearing thresholds as the quietest sound your ears are able to detect on a hearing exam. The loudness of sounds are measured in decibels (dBA). Decibels are also used to determine the quietest threshold you can hear. Thresholds are one of the most basic tools we use when referring to what is normal hearing verses a hearing loss. The softest sound most people with “normal” hearing can hear is referred to as audiometric zero – also referred to as 0dBHL (Decibel Hearing Level).
This threshold was first established In 1933, at the World’s Fair—a giant world gathering which included diversity from around the world. Audiological researchers performed hearing tests on thousands of people to develop a general idea of what is a “normal” threshold by averaging the softest sounds that people could hear at each frequency. Based on this research, even today, we still use this standard to determine the degree of people’s hearing loss.
Normal Hearing Is a Wide Range
Even though who are considered to have normal hearing, do so within a range. This can span from 0 dBHL all the way to 20 dBHL. A normal hearing is determined for anyone who can hear sounds as low as 20BHL, though some can even hear sounds below zero in the negative numbers. This means that normal is more of an average in which you still may have less hearing ability as someone else who also has “normal” hearing.
The average range in which people can most often detect sounds ranges from 0 to 180 dB. Even so, sounds from 0 to 20 are extremely soft.
What Is Hearing Loss?
On the other side of the range is the understanding that just because you can hear certain decibel levels, doesn’t mean they are safe. As a general rule, our ears can hear sounds below 85 dBA for 8 consistent hours. Past that point your ears are at a risk for irreversible hearing loss.
While we collect sounds with our ears, listening occurs in the brain. Our ears send sound to our brain via tiny hair like cells called stereocilia. Stereocilia convert audio vibrations into electrical impulses which the brain can translate. However, the stereocilia are incredibly fragile – especially when sounds surpass a safe listening level. Increased vibration for too long can cause the stereocilia to shatter against the membrane which holds them – causing irreversible danger.
Testing for Hearing Loss
If you just had a hearing test, and the results show that your hearing threshold is over 20 BHL, this indicates a hearing exam. This is often determined by placing you in a soundproof booth and playing sounds at various tones, volumes and pitches through headphones. The quietest sounds you can hear determine you level of hearing.
These are the average hearing thresholds at each degree of hearing loss:
- Normal hearing – your hearing threshold starts below 0 for some pitches and doesn’t rise above 25 dBA on any pitch.
- Mild hearing loss – You struggle to hear sounds softer than 26 dBA, to 40 dBA.
- Moderate hearing loss – your hearing thresholds are between 41 to 55 dBA.
- Moderately severe hearing loss – your hearing thresholds are between 56dBA to 70dBA, and you’re missing a significant softer sound in your environment such as whispering or the chirping of birds.
- Severe hearing loss – your hearing thresholds are between 71 dB to 90dBA. You struggle to hear normal everyday conversation
Baseline Hearing Test
If you have ever wondered the extent of your hearing, it’s always better to know than not. It’s common for people to be unaware of their hearing ability for years due to the subtle nature in which it develops. Another sign that it’s time to test is if you are 50 or older. While hearing loss can occur at any age, the risk goes up as we age. To stay safe and increase your quality of life, treat hearing loss before it gets to a dangerous level. Schedule a hearing exam today and find out all about your hearing ability.