Usually a person with this ability has had it all life, and it seems to be most commonly found among artists, writers, filmmakers, photographers, mathematicians and musicians.
Studies have found some factors such as a childhood with 2-3 languages spoken at home and early music training/education are common among “syns”.
The common ratio is known to be 1 in 1000.
Also, more women than men AND left handed persons seem to have the brain sending off extra feedback-signals between the right and the left side of the brain, inducing this state of extra sensory experience.
Usually, this sensitivity are found in several family-members, but it can skip some generations and suddenly “be there”.
It has NOTHING to do with medication, drug nor alcohol. Hallucinations due to either opiats or an accident/trauma to the head, may cause this experience, but these are temporary.