People who are blind from birth are often better than sighted people at processing certain aspects of sound. A mouse study hints at why: Even a few days in the dark helped "rewire" the auditory center of an adult animal's brain.
Figure 15 shows such frequency distribution along the length of the cochlea for both the incoming and outgoing waves. The strength of nerve signals also depends on the volume of the sound. This is interpreted by the brain as loudness. It is believed that tone is an interpretation of the brain based on the distribution of hair cells stimulated.
This hearing aid plus piercing combination is for the hardcore and hard of hearing. The PLUG looks like a large, popular piercing called a gauge, which comes in a variety of color combinations, which means you can easily personalize it to your aesthetic. Nonetheless, the punk rocker look likely only appeals to a very small crowd.