What is smell?

Question

What is smell?

Answer 1

Odor (or smell) is a sensation caused by odorant molecules dissolved in the air. The widest range of odors consist of organic compounds, although some inorganic substances, such as hydrogen sulfide and ammonia, are also odorants. The perception of an odor effect is a two step process. First, there is the physiological part; the sense of the stimulus by receptors in the nose. After that, the psychological part follows. The stimuli are processed by the region of the human brain which is responsible for smelling. Because of this, an objective and analytical measure of odor is impossible. While odor feelings are very personal perceptions, individual reactions are related to gender, age, state of health, and private affectations. Common odors that people are used to, such as their own body odor, are less noticeable to individuals than external or uncommon odors.

For most people, the process of smelling gives little information concerning the ingredients of a substance. It only offers information related to the emotional impact. Experienced people, however, such as flavorists and perfumers, can pick out individual chemicals in complex mixes through smell alone.