04-01-2016, 04:56 PM
Abstract
The relevance of perception of smell and the corresponding olfactory communication changed, and attitudes of cultures towards olfaction differed through the ages. Finally enlightened philosophers declared odour and the sense of smell as immeasurable, unimportant and therefore unusable for scientific purpose. But, ironically, in the last few years more and more artistic multimedia installations used odours, scented products were sold and the increasing application of aroma therapy indicate a changed attitude towards social odours. Emotionalizing scents are largely used for influencing customers’ behaviour in sales rooms and scientists are currently investigating the mystery of smell. The technological progress meanwhile allows for measuring and reproducing odours. Therefore odours are also becoming interesting for technical information transfer or communication, especially in Human-Computer Interaction. Smell seems to be an unrecognised medium and a new channel in multi-media. This paper presents various dimensions about olfaction and focuses on ongoing research and future challenges in digitizing smell and its transmission over internet.
What Is Smell?
1 Olfaction, the sense of smell, is the ability to use the nose to notice or discover the presence of an odorous substance in the air, that is, an odorant - a chemical compound that has a smell or odour. It is estimated that humans can detect 10,000 to 100,000 different odorants. We also have the capability to distinguish between slight variations in the chemical structure of some odorants, as well as being able to detect the presence of infinitesimally small amounts of certain odorants, e.g. dilutions of less than one part in several billion parts of air. Thus, while our sense of smell may not be as acute as that of other mammals, e.g. sheep dogs, bloodhounds, it is still quite sensitive and remarkably acute (Ward, P., Davies, B. & Kooijman, D. 2007; Well&Good 2004). Till 1991, it was not understood how the recognition and perception of the 10,000 or so odours that mammals can detect actually worked and then Linda B. Buck and Richard Axel discovered the existence of a gene family in mammals which encodes olfactory receptor types and were awarded the Nobel Prize for their discovery (Gardiner, M.B. Fall 2004; Nobelprize.org, 2004). They discovered the presence of about 600 of these odorant receptor genes, with about a half of them being non-functional pseudo genes, thus leaving humans with approximately 350 olfactory receptor types. Discovering the presence of the odorant receptor genes and the role they play in odour recognition and perception of smells was the first clue in a puzzle that researchers had been trying to solve for a long while.
Following this discovery, Buck and the rest of her research team then became preoccupied with solving the next part of the puzzle. They focused on finding out how it was possible for humans to have the ability to detect at least 10,000 different odorants with only 350 functional odorant receptor genes, and likewise for other mammals. Their research further revealed that the receptor types present in the olfactory receptor genes are used in a combinatorial manner to encode odour identities. That is, a single receptor is able to recognise multiple odorants, and a single odorant is recognised by multiple receptors, but that different odorants are recognised by different combinations of olfactory receptors. In this way, mappings of different combinations of odorant receptors create a vast array of different odour perceptions in mammals (Saltus, R., 2007; HHMI News, 2001).