What is Fragrance?
A fragrance is made from a pleasant smelling aroma compound. To be a fragrance the compound needs to be made of volatile chemicals that create an odor. The odor or fragrance has to have a smell that can be sensed by the olfactory receptors in the nose.
UNDERSTANDING ODOR PERCEPTION
Our sense of smell is located in two regions of our nasal mucous membranes.As soon as an odour molecule that has penetrated into the moucus layer is caught in a matching depression. The nerve cell sends a signal to the brain.
In the case of human being, olfactory sensitivity is fairly great. Many substances can even be percieved when diluted billions or even trillions of times.