Nails on a chalk board, squealing brakes, or a crying baby are all sounds that can make one’s skin crawl. Why does this happen? The answer involves how the brain processes sounds. When we detect a sound, sound waves travel to our ears and the sound energy is converted to nerve impulses. These impulses travel to the auditory cortex of the brain’s temporal lobes for processing. Another brain structure, the amygdala, heightens our perception of the sound and associates it with a particular emotion, such as fear or unpleasantness. These emotions can illicit a physical response to certain sounds, such as goose bumps or a sensation that something is crawling over your skin.