An intense and immediate emotional and physiological reaction (possibly rage, frustration, sadness, or panic) upon hearing certain sounds - most prominently noises associated with oral functions such as eating, breathing, chewing or other noises such as typing sounds or pencils scratching-are the defining symptoms of a little known and poorly understood condition called "Selective Sound Sensitivity Syndrome" or "4S".

Onset is typically around the time of puberty and appears to persist and in some cases, trigger noises expand, as time passes. Reactions can dominate lifestyle and occupational choices, lead to social isolation or psychological difficulties.

There appears to be evidence of a genetic component as the condition appears in family members. A certain percentage of people with 4S have also demonstrated signs of Obsessive Compulsive Disorder, and has been also associated with other pervasive conditions such as the Autism Spectrum. However, the vast majority of people with 4S do not appear to have other pervasive or obviously identifiable disorder.

This syndrome was first recognized by audiologist Dr. Marsha Johnson in 2002. Since that time, there has been no known research conducted by the scientific community, and to date there is no known cure. Medical and psychological therapies have included the use of medicine to address the secondary symptoms of anxiety, depression, or other symptoms, counseling to address the social and personal difficulties associated with the symptoms, alternative therapies including acupuncture, hypnosis, or natural remedies. To date, a single effective therapy has not been discovered.