I am the owner of an earbud (headphone) company and we have actually done numerous test to see if headphones can help with productivity. One of the more interesting tests was that even when our headphones were worn and not plugged in, productivity increased more than 25% in a loud work environment. This proves that the 'isolation' effect is enough on its own. The company is AirBuds

This was really insightful and refreshing. Everyone has the same capability to reason, so it was great to see that everyones brain is wired the same.