I've been diagnosed since I was younger (2nd grade) with a hearing impairment. Basically the nerve hairs on my cochlea are burned and I don't pick up 70% of the frequencies around me in my right ear.
My question is whether people can be born with a higher level of hearing? Or does it stop at 100% hearing, like 20/20 vision?
Short answer
People with above-normal hearing exist.
Background
Normal hearing was defined as the average of a group of young healthy individuals. These normal hearing levels are currently used to express acoustic sensitivities. One commonly used way is to use decibels relative to this normal hearing level (dB NH). This scale is used in audiograms (Schnupp et al., 2012). When hearing senstivities are reduced by 20 dB or more it is regarded as diagnostic for hearing impairment (Fig. 1).
Fig. 1. Audiogram. Source: (Schnupp et al., 2012)
Statistical outliers always exist. In Fig. 2 is an audiogram showing above-normal hearing sensitivities in the low frequencies in the left ear and in the high frequencies in the right ear (Fig. 2).
Fig. 2. Audiograms showing normal hearing (solid lines) and noise-induced hearing loss (dotted lines) Source: Fraser University, CA.
Reference
Schnupp et al., Auditory Neuroscience, MIT Press 2012
