Jacob Jolij and Maaike Meurs from Groningen University: Happy and sad music do not only change the way you feel but it also changes the way you perceive your environment. When you listen to sad music, you are more likely to notice sad faces and when you listen to happy music you are more likely to notice happy faces. Subjects even said they recognized a smiling face when there wasn't even one to see, but since they were in a happy mood that is what they perceived. Jolij said, "Seeing things that are not there is the result of top-down processes in the brain." The results "suggest that the brain builds up expectations not just on the basis of experience but on your mood as well."
Absolute pitch (perfect pitch): an auditory phenomenon characterized by the ability of a person to identify or re-create a given musical note without the benefit of a reference tone. Absolute pitch is not when a person can distinguish frequencies from one Hertz to another, it is when a person can recognize a catagory within that Hertz. It is a very impressive ability. People with absolute pitch can detect the quality sound of a choma. Also, people who don't have perfect pitch have just as good hearing as people with perfect pitch. Overall, people with perfect pitch have the ability to recognize certain pitches and distinguish between the rate of one sound or vibration to another one.