by Ruchira Paul
We don't have accurate standards for measuring smell. No yard stick like the wavelength of light, nor any criterion like scale, pitch or timbre that measure sound, exists for odor perception. We don't even have very good words to describe smells. Yet like sight and sound our sense of smell is a powerful component of our experience and memory.
The exact mechanism of olfaction is still being debated. Odors are defined by our reaction to them. Adjectives like overpowering, fruity, spicy, pungent, appetizing, stale, putrid etc. are used to describe smells. We have formulaic expressions such as bouquet, aroma, fragrance or stench which can encompass a whole host of different smells, unlike a precise word like “blue.” The best we can do sometimes is to compare a new smell to another familiar one. We resort to evocative similes such as “the restaurant had a dank odor like a musty cellar,” “her hair smelt of green apples,” “he reeked of alcohol and tobacco,” or “the garbage is stinking of rotten eggs.” We use abstract concepts for imagined odors – a smell like death, the acrid smell of fear, smelling victory. Impossible though it may be to put in words, we are constantly reacting to our environment through our sense of smell. Recording an odor in the brain can also trigger other physiological reactions – increase or decrease in appetite, nausea, feeling of cleanliness, relaxation, sexual arousal. We even smell danger. In the case of fire we often smell it burning before we see its light or feel its heat. Most of the time we are able to get a fair idea of what an odor may be like from its description, provided we are familiar with the reference through prior experience.
Smells are powerful reminders of our past experiences. It has been established that the olfactory memory stays with us long after visual memory has faded. Vivid childhood memories are very often intimately associated with distinct scents. We clearly remember festive days, our mother's proximity and mundane household routines from remembered smells. Most of us who are parents, forever recall the happy smell of an amalgamation of baby powder and regurgitated milk which dominated our senses when our children were infants. A particular scent in one place reminds us of another one far away. Many of us are reminded of the homes we have lived in and the places we have visited through odors. I have never encountered the very special fragrance of wet earth after the first monsoon rains break the oppressive monotony of the scorching summer heat, anywhere outside India. A pleasant smell does not necessarily evoke pleasant memories and neither is a foul odor always a reminder of an unpleasant one. A friend of mine could not stand the perfume of sandalwood; it reminded her of the day in childhood when her grandfather died and the house was redolent with the scent of sandalwood incense. On the other hand, the rather noxious reek produced by the intermingling vapors of benzene, acetone and acetic acid, the stock odor of all chemistry labs, to this day floods my mind with pleasing nostalgia for the earnest hours spent as a student and teacher of chemistry many moons ago.

