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It is well known that the olfactory sensitivity changes with exposure time and concentration of odor under continuous exposure to odor in the air. This decrease of odorous sensitivity, the increase of odorous threshold in other words due to continuous exposure to odor is called olfactory adaptation.
The object of this study is to make an olfactory model which can be applied for predicting the olfactory sensation. Firstly, the experiment was conducted to obtain the data of psychological response of odor intensity using a continuous scale of odor intensity under the odor concentration with step change on time serious. Ethyl acetate was used as the target odor.
Twelve panels (subjects) were employed for this experiment. These subjects smelled the odorous air blown out of a duct carrying the air injected with ethyl acetate with a controlled generation rate. As a result, it was turned out the odor intensity decreases exponentially as time due to olfactory adaptation.
Secondly, the theoretical olfactory model is constructed. This model is based on the impulse response function. By regression analysis on the varying odor intensity, two parameters of the exponential response function are identified. One parameter is the amplitude of response to unit impulse, and the other parameter is exponential constant. Odor intensity can be predicted under any variation of odor concentration by this theoretical model of response function. The accuracy of this olfactory model is examined by comparing the measured odor intensity with predicted odor intensity under odor concentration varying with steps in time series.
Lastly, this model is applied to some typical odor concentration variations, and the possibility of controlling ventilation rate to keep the intensity of body odor inside a room less than a certain level in order to save energy will be noted. In addition, calculation method of varying ventilation rate to control the odor will be presented.
Additionally, the model applicability was tested under recovery process of olfactory adaptation using instantaneous exposure of odor under recovering state with fresh air.
It is turned out that this theoretical olfactory model is quite useful to predict the odor intensity under adapting state rather than recovering process.