By definition, “normal” hearing is the absence of hearing loss. You might be surprised to learn, though, how “normal” hearing was established.
To understand “normal” hearing, one must first understand “audiometric zero.” Audiometric zero refers to the level of a pure tone of a given frequency that is minimally detectable (known as thresholds) by a person with normal hearing that isn't experiencing hearing loss.
To establish audiometric zero, researchers undertook thousands of hearing tests with people at the 1933 World’s Fair. They then took an average of the lowest level that participants could hear at particular frequencies. The result became a standard for what determined “normal hearing” and what determined hearing loss. They then created a standard formula to determine whether a person has hearing loss.
Normal hearing is actually a range of decibel levels from 0 dBHL (Decibel Hearing Level) — which is audiometric zero — to 20 dBHL. If a person’s hearing threshold is between 0 dBHL and 20 dBHL, the hearing is within normal limits. Hearing loss is identified as any threshold at any frequency that is over 20 dBHL. These results are all defined during a standard hearing test with a local hearing specialist.
It’s important to remember that some frequencies tested can be within normal limits yet scores at other frequencies may indicate hearing loss.
If you suspect that you or a loved one have hearing loss or if you’d like to confirm that your hearing is normal, it’s recommended you consult with a local hearing healthcare professional. To find one near you, call 08000 683 533 or click here and we can help.