So you know what 20/20 vision is, it’s when you have perfect vision. But what is the equivalent for your ears? Well I think it should be called 20/20 audition; let me explain why…
20/20 vision is defined as how well you can see at 20 feet away, with 20/20 being what you should be able to see with clarity. However if you have 20/100 vision, you have to be 20 feet away to see something that someone with perfect sight can see at 100 feet away. “So what does that have to do with sound” I hear you cry, “last time I checked you can’t see sound!”. If you said that, you would be right, however the 20/20 part is to do with how we measure hearing.
Hearing is measured by how quiet you can hear sound (your hearing threshold) at different frequencies. Because sound is created by vibrations, we measure frequency by the number of vibrations per second (which we call hertz or Hz for short). 20Hz is the lowest we can hear, which literally means 20 vibrations per second and 20,000Hz is the highest we can hear, which is 20,000 vibrations per second. For hearing tests, a sound of a known frequency is played and the listener adjusts it to the quietest point at which they can only just hear it. This level is then compared to what the level should be for perfect hearing and the difference is the hearing loss at that frequency.
As we become older, we lose sensitivity in our ears, particularly at higher and lower frequencies, meaning the range that we can hear is reduced. As perfect hearing goes from 20Hz to 20kHz (20,000Hz), this is why I think it should be called 20/20 audition (audition is just another word for hearing). From what I could seem to find online, there wasn’t a term for perfect hearing like there is for sight, only “normal hearing”, which seems a bit boring to me. Do you agree with me, or if not what do you think perfect hearing should be called?
 What is 20/20 vision? – http://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/visual-acuity
 What is normal hearing? – http://www.bio.net/mm/audiolog/1998-June/004067.html
 How is hearing measured? – http://www.dosits.org/science/soundmeasurement/hearingmeasured/