After serious research into the matter, it’s now understood that it’s actually some of the lower-frequency sound vibrations involved in this action that trigger the aversion response, and not the squeaky higher ones you might suspect.
But why do some people have this response? Some researchers say it might be a physiological throwback to the wild jungle days of human history. As evidence, they point to the fact that the screeching chalkboard sound resembles the danger sounds of some primates.
Based on our simian heritage, humans likely had a similar warning sound in the distant past, and it may be that when we respond to a chalkboard sound, we’re hearing the residual echoes of a warning hardwired into our systems a long time ago.
Researchers have also found that the sound of Styrofoam being rubbed together is the second most irritating sound next to fingernails on a chalkboard.